Selected quad for the lemma: end_n

Word A Word B Word C Word D Occurrence Frequency Band MI MI Band Prominent
end_n draw_v line_n straight_a 2,138 5 12.9115 5 true
View all documents for the selected quad

Text snippets containing the quad

ID Title Author Corrected Date of Publication (TCP Date of Publication) STC Words Pages
A38722 The elements of Euclid, explained and demonstrated in a new and most easie method with the uses of each proposition in all the parts of the mathematicks / by Claude Francois Milliet D'Chales, a Jesuit ; done out of French, corrected and augmented, and illustrated with nine copper plates, and the effigies of Euclid, by Reeve Williams ...; Huict livres des Eléments d'Euclide rendus plus faciles. English Dechales, Claude-François Milliet, 1621-1678.; Euclid. Elements.; Williams, Reeve, fl. 1682-1703. 1685 (1685) Wing E3399; ESTC R10241 136,603 430

There are 4 snippets containing the selected quad. | View original text

whereon_o the_o head_n thereof_o you_o shall_v find_v the_o book_n it_o belong_v to_o and_o the_o proposition_n or_o use_n continue_v in_o their_o order_n eight_o book_n of_o euclid_n element_n with_o the_o use_v of_o each_o proposition_n the_o first_o book_n euclid_n design_n in_o this_o book_n be_v to_o give_v the_o first_o principle_n of_o geometry_n and_o to_o do_v the_o same_o methodical_o he_o begin_v with_o the_o definition_n and_o explication_n of_o the_o most_o ordinary_a term_n than_o he_o exhibit_v certain_a supposition_n and_o have_v propose_v those_o maxim_n which_o natural_a reason_n teach_v he_o pretend_v to_o put_v forward_o nothing_o without_o demonstration_n and_o to_o convince_v any_o one_o which_o will_v consent_v to_o nothing_o but_o what_o he_o shall_v be_v oblige_v to_o acknowledge_v in_o his_o first_o proposition_n he_o treat_v of_o line_n and_o of_o the_o several_a angle_n make_v by_o their_o intersect_v each_o other_o and_o have_v occasion_n to_o demonstrate_v their_o propriety_n and_o compare_v certain_a triangle_n he_o do_v the_o same_o in_o the_o first_o eight_o proposition_n then_o teach_v the_o practical_a way_n of_o divide_v a_o angle_n and_o a_o line_n into_o two_o equal_a part_n and_o to_o draw_v a_o perpendicular_a he_o pursue_v to_o the_o propriety_n of_o a_o triangle_n and_o have_v show_v those_o of_o parallel_n line_n he_o make_v a_o end_n of_o the_o explication_n of_o this_o first_o figure_n and_o pass_v forward_o to_o parallellogram_n give_v a_o way_n to_o reduce_v all_o sort_n of_o polygon_n into_o a_o more_o regular_a figure_n he_o end_v this_o book_n with_o that_o celebrate_a proposition_n of_o pythagoras_n and_o demonstrate_v that_o in_o a_o rectangular_a triangle_n the_o square_a of_o the_o base_a be_v equal_a to_o the_o sum_n of_o the_o square_n of_o the_o side_n include_v the_o right_a angle_n definition_n 1._o a_o point_n be_v that_o which_o have_v no_o part_n this_o definition_n be_v to_o be_v understand_v in_o this_o sense_n the_o quantity_n which_o we_o conceive_v without_o distinguish_v its_o part_n or_o without_o think_v that_o it_o have_v any_o be_v a_o mathematical_a point_n far_o differ_v from_o those_o of_o zeno_n which_o be_v altogether_o indivisible_a since_o one_o may_v doubt_v with_o a_o great_a deal_n of_o reason_n if_o those_o last_o be_v possible_a which_o yet_o we_o can_v of_o the_o first_o if_o we_o conceive_v they_o as_o we_o ought_v 2._o a_o line_n be_v a_o length_n without_o breadth_n the_o sense_n of_o this_o definition_n be_v the_o same_o with_o that_o of_o the_o forego_n the_o quantity_n which_o we_o consider_v have_v length_n without_o make_v any_o reflection_n on_o its_o breadth_n be_v that_o we_o understand_v by_o the_o word_n line_n although_o one_o can_v draw_v a_o real_a line_n which_o have_v not_o a_o determinate_a breadth_n it_o be_v general_o say_v that_o a_o line_n be_v produce_v by_o the_o motion_n of_o a_o point_n which_o we_o ought_v well_o to_o take_v notice_n of_o see_v that_o by_o a_o motion_n after_o that_o manner_n may_v be_v produce_v all_o sort_n of_o quantity_n imagine_v then_o that_o a_o point_n move_v and_o that_o it_o leave_v a_o trace_n in_o the_o middle_n of_o the_o way_n which_o it_o pass_v the_o trace_v be_v a_o line_n 3._o the_o two_o end_n of_o a_o line_n be_v point_n 4._o a_o straight_a line_n be_v that_o who_o point_n be_v place_v exact_o in_o the_o midst_n or_o if_o you_o will_v rather_o have_v it_o a_o straight_a line_n be_v the_o short_a of_o all_o the_o line_n which_o may_v be_v draw_v from_o one_o point_n to_o another_o 5._o a_o superficies_n be_v a_o quantity_n to_o which_o be_v give_v length_n and_o breadth_n without_o consider_v the_o thickness_n 6._o the_o extremity_n of_o a_o superficies_n be_v line_n 7._o a_o plain_a or_o straight_o superficies_n be_v that_o who_o line_n be_v place_v equal_o between_o the_o extremity_n or_o that_o to_o which_o a_o straight_a line_n may_v be_v apply_v any_o manner_n of_o way_n 1._o plate_n i._n fig._n 1._o i_o have_v already_o take_v notice_n that_o motion_n be_v capable_a of_o produce_v all_o sort_n of_o quantity_n whence_o we_o say_v that_o when_o a_o line_n pass_v over_o another_o it_o produce_v a_o superficies_n or_o a_o plain_n and_o that_o that_o motion_n have_v a_o likeness_n to_o arithmetical_a multiplication_n imagine_v that_o the_o line_n ab_fw-la move_v along_o the_o line_n bc_n keep_v the_o same_o situation_n without_o incline_v one_o way_n or_o the_o other_o the_o point_n a_o shall_v describe_v the_o line_n ad_fw-la the_o point_n b_o the_o line_n bc_n and_o the_o other_o point_n between_o other_o parallel_n line_n which_o shall_v compose_v the_o superficies_n abcd._n i_o add_v that_o this_o motion_n correspond_v with_o arithmetical_a multiplication_n for_o if_o i_o know_v the_o number_n of_o point_n which_o be_v in_o the_o line_n ab_fw-la bc_n multiply_v of_o they_o one_o by_o the_o other_o i_o shall_v have_v the_o number_n of_o point_n which_o compose_v the_o superficies_n abcd_v as_o if_o ab_fw-la contain_v four_o point_n and_o bc_n six_o say_v four_o time_n six_o be_v twenty_o four_o the_o superficies_n ab_fw-la cd_o shall_v be_v compose_v of_o twenty_o four_o point_n now_o i_o may_v take_v for_o a_o mathematical_a point_n any_o quantity_n whatsoever_o for_o example_n a_o foot_n provide_v i_o do_v not_o subdivide_v the_o same_o into_o part_n 8._o a_o plain_a angle_n be_v the_o open_n of_o two_o line_n which_o intersect_v each_o other_o and_o which_o compose_v not_o one_o single_a line_n 2._o fig._n 2._o as_o the_o opening_z d_o of_o the_o line_n ab_fw-la cb_n which_o be_v not_o part_n of_o the_o same_o line_n a_o right_a line_a angle_n be_v the_o open_n of_o two_o straight_a line_n it_o be_v principal_o of_o this_o sort_n of_o angle_n which_o i_o intend_v to_o treat_v of_o at_o present_a because_o experience_n do_v make_v i_o perceive_v that_o the_o most_o part_n of_o those_o who_o begin_v do_v mistake_v the_o measure_v the_o quantity_n of_o a_o angle_n by_o the_o length_n of_o the_o line_n which_o compose_v the_o same_o 4._o fig._n 3_o 4._o the_o most_o open_a angle_n be_v the_o great_a that_o be_v to_o say_v when_o the_o line_n include_v a_o angle_n be_v far_o asunder_o than_o those_o of_o another_o angle_n take_v they_o at_o the_o same_o distance_n from_o the_o point_n of_o intersection_n of_o their_o line_n the_o first_o be_v great_a than_o the_o second_o so_o the_o angle_n a_o be_v great_a than_o e_z because_o if_o we_o take_v the_o point_n b_o and_o d_o as_o far_o distant_a from_o the_o point_n a_o as_o the_o point_n g_o and_o l_o be_v from_o the_o point_n e_o the_o point_n b_o and_o d_o be_v far_o asunder_o than_o the_o point_n g_o and_o l_o from_o whence_o i_o conclude_v that_o if_o eglantine_n el_fw-es be_v continue_v the_o angle_n e_o will_v be_v of_o the_o same_o measure_n and_o less_o than_o the_o angle_n a._n we_o make_v use_v of_o three_o letter_n to_o express_v a_o angle_n and_o the_o second_o letter_n denote_v the_o angular_a point_n as_o the_o angle_n bad_a be_v the_o angle_n which_o the_o line_n ba_o ad_fw-la do_v form_n at_o the_o point_n a_o the_o angle_n bac_n be_v that_o which_o be_v form_v by_o the_o line_n ba_o ac_fw-la the_o angle_n god_n be_v comprehend_v under_o the_o line_n ca_n ad._n 3._o fig._n 3._o the_o arch_n of_o a_o circle_n be_v the_o measure_n of_o a_o angle_n thus_o design_v to_o measure_v the_o quantity_n of_o the_o angle_n bad_a i_o put_v one_o foot_n of_o the_o compass_n on_o the_o point_v a_o and_o with_o the_o other_o i_o describe_v a_o arch_n of_o a_o circle_n bcd_v the_o angle_n shall_v be_v the_o great_a by_o how_o much_o the_o arch_n bcd_v which_o be_v the_o measure_n thereof_o shall_v contain_v a_o great_a portion_n of_o a_o circle_n and_o because_o that_o common_o a_o arch_n of_o a_o circle_n be_v divide_v into_o three_o hundred_o and_o sixty_o equal_a part_n call_v degree_n it_o be_v say_v that_o a_o angle_n contain_v twenty_o thirty_o forty_o degree_n when_o the_o arch_n include_v betwixt_o its_o line_n contain_v twenty_o thirty_o forty_o degree_n so_o the_o angle_n be_v great_a which_o contain_v the_o great_a number_n of_o degree_n as_o the_o angle_n bad_a be_v great_a than_o gel_n the_o line_n ca_n divide_v the_o angle_n bad_a in_o the_o middle_n because_o the_o arch_n bc_n cd_o be_v equal_a and_o the_o angle_n bac_n be_v a_o part_n of_o bad_a because_o the_o arch_a bc_n be_v part_n of_o the_o arch_n bd._n 10._o when_o a_o line_n fall_v on_o another_o line_n make_v the_o angle_n on_o each_o side_n thereof_o equal_a those_o angles_n be_v right_a angle_n and_o the_o line_n so_o fall_v be_v a_o perpendicular_a 5._o fig._n 5._o as_o if_o the_o line_n ab_fw-la fall_v on_o cd_o
superficies_n 18._o a_o cone_n be_v a_o figure_n make_v when_o one_o side_n of_o a_o right_a angle_a triangle_n viz._n one_o of_o those_o that_o contain_v the_o right_a angle_n remain_v fix_v the_o triangle_n be_v turn_v round_o about_o till_o it_o return_v to_o the_o place_n from_o whence_o it_o first_o move_v and_o if_o the_o fix_a right_a line_n be_v equal_a to_o the_o other_o which_o contain_v the_o right_a angle_n than_o the_o cone_n be_v a_o rectangled_a cone_n but_o if_o it_o be_v less_o it_o be_v a_o obtuse_a angle_a cone_n if_o great_a a_o acute_a angle_a cone_n 19_o the_o axis_n of_o a_o cone_n be_v that_o fix_a line_n about_o which_o the_o triangle_n be_v move_v 20._o a_o cylinder_n be_v a_o figure_n make_v by_o the_o move_a round_n of_o a_o right_a angle_a parallelogram_n one_o of_o the_o side_n thereof_o namely_o which_o contain_v the_o right_a angle_n abide_v fix_v till_o the_o parallelogram_n be_v turn_v about_o to_o the_o same_o place_n whence_o it_o begin_v to_o move_v 21._o like_a cones_n and_o cylinder_n be_v those_o who_o axe_n and_o diameter_n of_o their_o base_n be_v proportional_a cones_n be_v right_a when_o the_o axis_n be_v perpendicular_a to_o the_o plain_a of_o the_o base_a and_o they_o be_v say_v to_o be_v scalene_n when_o the_o axis_n be_v incline_v to_o the_o base_a and_o the_o diameter_n of_o their_o base_n be_v in_o the_o same_o ratio_fw-la we_o add_v that_o incline_v cones_n to_o be_v like_o their_o axe_n must_v have_v the_o same_o inclination_n to_o the_o plane_n of_o their_o base_n proposition_n i._o theorem_fw-la i._n plate_n vii_o prop._n i._n a_o straight_a line_n can_v have_v one_o of_o its_o part_n in_o a_o plane_n and_o the_o other_o without_o it_o if_o the_o line_n ab_fw-la be_v in_o the_o plane_n ad_fw-la it_o be_v continue_v shall_v not_o go_v without_o but_o all_o its_o part_n shall_v be_v in_o the_o same_o plane_n for_o if_o it_o can_v be_v that_o bc_n be_v a_o part_n of_o ab_fw-la continue_v draw_v in_o the_o plane_n cd_o the_o line_n bd_o perpendicular_a to_o ab_fw-la draw_v also_o in_o the_o same_o plane_n be_v perpendicular_a to_o bd._n demonstration_n the_o angle_n abdella_n bde_n be_v both_o right_a angle_n thence_o by_o the_o 14_o of_o the_o first_o ab_fw-la be_v do_v make_v but_o one_o line_n and_o consequent_o bc_n be_v not_o a_o part_n of_o the_o line_n ab_fw-la continue_v otherwise_o two_o strait_a line_n cb_n ebb_n will_v have_v the_o same_o part_n ab_fw-la that_o be_v ab_fw-la will_v be_v part_n of_o both_o which_o we_o have_v reject_v as_o false_a in_o the_o thirteen_o maxim_n of_o the_o first_o book_n use_v we_o establish_v on_o this_o proposition_n a_o principle_n in_o gnomonic_n to_o prove_v that_o the_o shadow_n of_o the_o stile_n fall_v not_o without_o the_o plane_n of_o a_o great_a circle_n in_o which_o the_o sun_n be_v see_v that_o the_o end_n or_o top_n of_o the_o stile_n be_v take_v for_o the_o centre_n of_o the_o heaven_n and_o consequent_o for_o the_o centre_n of_o all_o the_o great_a circle_n the_o shadow_n be_v always_o in_o a_o straight_a line_n with_o the_o ray_n draw_v from_o the_o sun_n to_o the_o opaque_fw-fr body_n this_o ray_n be_v in_o any_o great_a circle_n the_o shadow_n must_v also_o be_v therein_o proposition_n ii_o theorem_fw-la line_n which_o cut_v one_o another_o be_v in_o the_o same_o plane_n as_o well_o as_o all_o the_o part_n of_o a_o triangle_n if_o the_o two_o line_n be_v cd_o cut_v one_o another_o in_o the_o point_n a_o and_o if_o there_o be_v make_v a_o triangle_n by_o draw_v the_o base_a bc_n i_o say_v that_o all_o the_o part_n of_o the_o triangle_n abc_n be_v in_o the_o same_o plane_n and_o that_o the_o line_n be_v cd_o be_v likewise_o therein_o demonstration_n it_o can_v be_v say_v that_o any_o one_o part_n of_o the_o triangle_n abc_n be_v in_o a_o plane_n and_o that_o the_o other_o part_n be_v without_o without_o say_v that_o one_o part_n of_o a_o line_n be_v in_o one_o plane_n and_o that_o the_o other_o part_n of_o the_o same_o line_n be_v not_o therein_o which_o be_v contrary_a to_o the_o first_o proposition_n and_o see_v that_o the_o side_n of_o the_o triangle_n be_v in_o the_o same_o plane_n wherein_o the_o triangle_n be_v the_o line_n be_v cd_o shall_v be_v in_o the_o same_o plane_n use_v this_o proposition_n do_v sufficient_o determine_v a_o plane_n by_o two_o straight_a line_n mutual_o intersect_v each_o other_o or_o by_o a_o triangle_n i_o have_v make_v use_n thereof_o in_o optic_n to_o prove_v that_o the_o objective_a parallel_n line_n which_o fall_v on_o the_o tablet_n aught_o to_o be_v represent_v by_o line_n which_o concur_v in_o a_o point_n proposition_n iii_o theorem_fw-la the_o common_a section_n of_o two_o place_n be_v a_o straight_a line_n if_o two_o planes_n ab_fw-la cd_o cut_v one_o another_o their_o common_a section_n of_o shall_v be_v a_o straight_a line_n for_o if_o it_o be_v not_o take_v two_o point_n common_a to_o both_o plane_n which_o let_v be_v e_o and_o f_o and_o draw_v a_o strait_a line_n from_o the_o point_n e_o to_o the_o point_n f_o in_o the_o plane_n ab_fw-la which_o let_v be_v ehf_n draw_v also_o in_o the_o plane_n cd_o a_o straight_a line_n from_o e_o to_o f_o if_o it_o be_v not_o the_o same_o with_o the_o former_a let_v it_o be_v egf_n demonstration_n those_o line_n draw_v in_o the_o two_o plane_n be_v two_o different_a line_n and_o they_o comprehend_v a_o space_n which_o be_v contrary_a to_o the_o twelve_o maxim_n thence_o they_o be_v but_o one_o line_n which_o be_v in_o both_o plane_n shall_v be_v their_o common_a section_n use_v this_o proposition_n be_v fundamental_a we_o do_v suppose_v it_o in_o gnomonic_n when_o we_o represent_v in_o a_o dial_n the_o circle_n of_o the_o hour_n mark_v only_o the_o common_a section_n of_o their_o plane_n and_o that_o of_o the_o wall_n proposition_n iu_o theorem_fw-la if_o a_o line_n be_v perpendicular_a to_o two_o other_o line_n which_o cut_v one_o another_o it_o shall_v be_v also_o perpendicular_a to_o the_o plane_n of_o those_o line_n if_o the_o line_n ab_fw-la be_v perpendicular_a to_o the_o line_n cd_o of_o which_o cut_v one_o another_o in_o the_o point_n b_o in_o such_o manner_n that_o the_o angel_n abc_n abdella_n abe_n abf_n be_v right_a which_o a_o flat_a figure_n can_v represent_v it_o shall_v be_v perpendicular_a to_o the_o plane_n cd_o of_o that_o be_v to_o say_v that_o it_o shall_v be_v perpendicular_a to_o all_o the_o line_n that_o be_v draw_v in_o that_o plane_n through_o the_o point_n b_o as_o to_o the_o line_n gbh_n let_v equal_a line_n be_v cut_v bc_n bd_o be_v bf_n and_o let_v be_v draw_v the_o line_n aec_fw-la df_n ac_fw-la ad_fw-la ae_n of_o agnostus_n and_z ah_o demonstration_n the_o four_o triangle_n abc_n abdella_n abe_n abf_n have_v their_o angle_n right_o in_o the_o point_n b_o and_o the_o side_n bc_n bd_o be_v bf_n equal_a with_o the_o side_n ab_fw-la common_a to_o they_o all_o therefore_o their_o base_n ac_fw-la ad_fw-la ae_n of_o be_v equal_a by_o the_o four_o of_o the_o one_a 2._o the_o triangle_n ebc_n dbf_n shall_v be_v equal_a in_o every_o respect_n have_v the_o side_n bc_n bd_o be_v bf_n equal_a and_o the_o angel_n cbe_n dbf_n opposite_a at_o the_o vertex_fw-la be_v equal_a so_o than_o the_o angle_n be_v bdf_n bec_n bfd_n shall_v be_v equal_a by_o the_o four_o of_o the_o first_o and_o their_o base_n aec_fw-la df_n equal_a 3._o the_o triangle_n gbc_n dbh_n have_v their_o opposite_a angle_n cbg_n dbh_n equal_a as_o also_o the_o angle_n bdh_fw-mi bcg_n and_o the_o side_n bc_n bd_o they_o shall_v then_o have_v by_o the_o 26_o of_o the_o one_a their_o side_n bg_n bh_n cg_n dh_n equal_a 4._o the_o triangle_n ace_n afd_v have_v their_o side_n ac_fw-la ad_fw-la ae_n of_o equal_a and_o the_o base_n aec_fw-la df_n equal_a they_o shall_v have_v by_o the_o 8_o of_o the_o one_a the_o angles_n adf_n ace_n equal_a 5._o the_o triangle_n acg_n adh_n have_v the_o side_n ac_fw-la ad_fw-la cg_n dh_n equal_a with_o the_o angles_n adh_n agc_n thence_o they_o shall_v have_v their_o base_n agnostus_n ah_o equal_a last_o the_o triangle_n abh_n abg_n have_v all_o their_o side_n equal_a thence_o by_o the_o 27_o of_o the_o one_a the_o angles_n abg_n abh_n shall_v be_v equal_a and_o the_o line_n ab_fw-la perpendicular_a to_o gh_v so_o then_o the_o line_n ab_fw-la shall_v be_v perpendicular_a to_o any_o line_n which_o may_v be_v draw_v through_o the_o point_n b_o in_o the_o plane_n of_o the_o line_n cd_o of_o which_o i_o call_v perpendicular_a to_o the_o plane_n use_v this_o proposition_n come_v often_o in_o use_n in_o the_o first_o book_n of_o theodosius_n for_o example_n to_o demonstrate_v that_o the_o axis_n of_o the_o world_n be_v
the_o square_n of_o the_o other_o two_o sides_n ab_fw-la ac_fw-la draw_v the_o line_n ah_o parallel_n to_o bd_o ce_fw-fr and_o draw_v also_o the_o line_n ad_fw-la ae_n fc_n bg_n i_o prove_v that_o the_o square_a of_o be_v equal_a to_o the_o right_o angle_a figure_n or_o long_a square_a bh_n and_o the_o square_a agnostus_n to_o the_o right_o angle_a figure_n ch_z and_o that_o so_o the_o square_n be_v be_v equal_a to_o the_o two_o square_n of_o ag._n demonstration_n the_o triangle_n fbc_n abdella_n have_v their_o sides_n ab_fw-la bf_n bd_o bc_n equal_a and_o the_o angel_n fbc_n abdella_n be_v equal_a see_v that_o each_o of_o they_o beside_o the_o right_a angle_n include_v the_o angle_n abc_n thence_o by_o the_o 4_o the_o triangle_n abdella_n fbc_n be_v equal_a now_o the_o square_n of_o be_v double_a to_o the_o triangle_n fbc_n by_o the_o 41_o because_o they_o have_v the_o same_o base_a bf_n and_o be_v between_o the_o same_o parallel_n bf_a ac_fw-la likewise_o the_o right_o line_a figure_n bh_n be_v double_a to_o the_o triangle_n abdella_n see_v they_o have_v the_o same_o base_a bd_o and_o be_v between_o the_o same_o parallel_n bd_o ah_o therefore_o the_o square_n of_o be_v equal_a to_o the_o right_o line_a figure_n bh_n after_o the_o same_o manner_n the_o triangle_n ace_n gcb_n be_v equal_a by_o the_o 4_o the_o square_a agnostus_n be_v double_a the_o triangle_n bcg_n and_o the_o right_o line_a figure_n ch_n be_v double_a the_o triangle_n ace_n by_o the_o 41_o thence_o the_o square_a agnostus_n be_v equal_a to_o the_o right_o line_a figure_n ch_z and_o by_o consequence_n the_o sum_n of_o the_o square_n of_o agnostus_n be_v equal_a to_o the_o square_a bdec_n use_v 47._o use_v 47._o it_o be_v say_v that_o pythagoras_n have_v find_v this_o proposition_n sacrifice_v one_o hundred_o ox_n in_o thanks_o to_o the_o muse_n it_o be_v not_o without_o reason_n see_v this_o proposition_n serve_v for_o a_o foundation_n to_o a_o great_a part_n of_o the_o mathematics_n for_o in_o the_o first_o place_n trigonometry_n can_v be_v without_o it_o because_o it_o be_v necessary_a to_o make_v the_o table_n of_o all_o the_o line_n that_o can_v be_v draw_v within_o a_o circle_n that_o be_v to_o say_v of_o chord_n of_o sines_n also_o tangent_n and_o secant_v which_o i_o shall_v here_o show_v by_o one_o example_n let_v it_o be_v suppose_v that_o the_o semi-diameter_n ab_fw-la be_v divide_v into_o 10000_o part_n and_o that_o the_o arch_a bc_n be_v 30_o degree_n see_v the_o chord_n or_o subtendent_fw-la of_o 60_o degree_n be_v equal_a to_o the_o semi-diameter_n ac_fw-la bd_o the_o sine_fw-la of_o 30_o degree_n shall_v be_v equal_a to_o the_o half_a of_o ac_fw-la it_o shall_v therefore_o be_v 5000_o in_o the_o right_o angle_a triangle_n adb_n the_o square_a of_o ab_fw-la be_v equal_a to_o the_o square_n of_o bd_o and_o ad_fw-la make_v then_o the_o square_n of_o ab_fw-la by_o multiply_v 10000_o by_o 10000_o and_o from_o that_o product_n subtract_v the_o square_n of_o bd_o 5000_o there_o remain_v the_o square_a of_o ad_fw-la or_o bf_n the_o sine_fw-la of_o the_o compliment_n and_o extract_v the_o square_a root_n there_o be_v find_v the_o line_n fb_n then_o if_o by_o the_o rule_n of_o three_o you_o say_v as_o ad_fw-la be_v to_o bd_o so_o be_v ac_fw-la to_o ce_fw-fr you_o shall_v have_v the_o tangent_fw-la ce_fw-fr and_o add_v together_o the_o square_n of_o ac_fw-la ce_fw-fr you_o shall_v have_v by_o the_o 47_o the_o square_a of_o ae_n and_o by_o extract_v the_o root_n thereof_o you_o shall_v have_v the_o length_n of_o the_o line_n ae_n the_o secant_fw-la use_v 47._o we_o augment_v figure_n as_o much_o as_o we_o please_v by_o this_o proposition_n example_n to_o double_v the_o square_n abcd_v continue_v the_o side_n cd_o and_o make_v de_fw-fr equal_a to_o ad_fw-la the_o square_a of_o ae_n shall_v be_v the_o double_a of_o the_o square_n of_o abcd_n see_v that_o by_o the_o 47_o it_o be_v equal_a to_o the_o square_n of_o ad_fw-la and_o de._n and_o make_v a_o right_a angle_n aef_n and_o take_v of_o equal_a to_o ab_fw-la the_o square_a of_o of_o shall_v be_v triple_a to_o abcd._n and_o make_v again_o the_o right_a angle_n afg_v and_o fg_v equal_a to_o ab_fw-la the_o square_a of_o agnostus_n shall_v be_v quadruple_a to_o to_o abcd._n what_o i_o here_o say_v of_o a_o square_a be_v to_o be_v understand_v of_o all_o figure_n which_o be_v alike_o that_o be_v to_o say_v of_o the_o same_o species_n proposition_n xlviii_o theorem_fw-la if_o the_o two_o square_n make_v upon_o the_o side_n of_o a_o triangle_n be_v equal_a to_o the_o square_n make_v on_o the_o other_o side_n than_o the_o angle_n comprehend_v under_o the_o two_o other_o side_n of_o the_o triangle_n be_v a_o right_a angle_n if_o the_o square_a of_o the_o side_n np_n be_v equal_a to_o the_o square_n of_o the_o sides_n nl_n lp_n take_v together_o the_o angle_n nlp_n shall_v be_v a_o right_a angle_n draw_v lr_n perpendicular_a to_o nl_n and_o equal_a to_o lp_v then_o draw_v the_o line_n nr_n demonstration_n in_o the_o right_o angle_a triangle_n nlr_n the_o square_a of_o nr_n be_v equal_a to_o the_o square_n of_o nl_n and_o of_o lr_n or_o lp_v by_o the_o 47_o now_o the_o square_n of_o np_n be_v equal_a to_o the_o same_o square_n of_o nl_n lp_v therefore_o the_o square_n of_o nr_n be_v equal_a to_o that_o of_o np_n and_o by_o consequence_n the_o line_n nr_n np_n be_v equal_a and_o because_o the_o triangle_n nlr_n nlp_n have_v each_o of_o they_o the_o side_n nl_n common_a and_o that_o their_o base_n rn_v np_n be_v also_o equal_a the_o angel_n nlp_n nlr_n shall_v be_v equal_a by_o the_o 8_o and_o the_o angle_n nlr_n be_v a_o right_a angle_n the_o angle_z nlp_n shall_v be_v also_o a_o right_a angle_n the_o end_n of_o the_o first_o book_n the_o second_o book_n of_o euclid_n element_n euclid_n treat_v in_o this_o book_n of_o the_o power_n of_o straight_a line_n that_o be_v to_o say_v of_o their_o square_n compare_v the_o divers_a rectangle_v which_o be_v make_v on_o a_o line_n divide_v as_o well_o with_o the_o square_a as_o with_o the_o rectangle_n of_o the_o whole_a line_n this_o part_n be_v very_o useful_a see_v it_o serve_v for_o a_o foundation_n to_o the_o practical_a principle_n of_o algebra_n the_o three_o first_o proposition_n demonstrate_v the_o three_o rule_n of_o arithmetic_n the_o four_o teach_v we_o to_o find_v the_o square_a root_n of_o any_o number_n whatsoever_o those_o which_o follow_v unto_o the_o eight_o serve_v in_o several_a accident_n happen_v in_o algebra_n the_o remain_a proposition_n to_o the_o end_n of_o this_o book_n be_v conversant_a in_o trigonometry_n this_o book_n appear_v at_o the_o first_o sight_n very_o difficult_a because_o one_o do_v imagine_v that_o it_o contain_v mysterious_a or_o intricate_a matter_n notwithstanding_o the_o great_a part_n of_o the_o demonstration_n be_v found_v on_o a_o very_a evident_a principle_n viz._n that_o the_o whole_a be_v equal_a to_o all_o its_o part_n take_v together_o therefore_o one_o ought_v not_o to_o be_v discourage_v although_o one_o do_v not_o apprehend_v the_o demonstration_n of_o this_o book_n at_o the_o first_o read_v definition_n boook_v def._n 1._o of_o the_o second_o boook_v a_o rectangular_a parallelogram_n be_v comprehend_v under_o two_o right_a line_n which_o at_o their_o intersection_n contain_v a_o right_a angle_n it_o be_v to_o be_v note_v henceforward_o that_o we_o call_v that_o figure_n a_o rectangular_a parallelogram_n which_o have_v all_o its_o angle_n right_o and_o that_o the_o same_o shall_v be_v distinguish_v as_o much_o at_o be_v requisite_a if_o we_o give_v thereto_o length_n and_o breadth_n name_v only_o two_o of_o its_o line_n which_o comprehend_v any_o one_o angle_n as_o the_o line_n ab_fw-la bc_n for_o the_o rectangular_a parallelogram_n abcd_v be_v comprehend_v under_o the_o line_n ab_fw-la bc_n have_v bc_n for_o its_o length_n and_o ab_fw-la for_o its_o breadth_n whence_o it_o be_v not_o necessary_a to_o mention_v the_o other_o line_n because_o they_o be_v equal_a to_o those_o already_o speak_v of_o i_o have_v already_o take_v notice_n that_o the_o line_n ab_fw-la be_v in_o a_o perpendicular_a position_n in_o respect_n of_o bc_n produce_v the_o rectangle_n abcd_n if_o move_v along_o the_o line_n bc_n and_o that_o this_o motion_n represent_v arithmetical_a multiplication_n in_o this_o manner_n as_o the_o line_n ab_fw-la move_v along_o the_o line_n bc_n that_o be_v to_o say_v take_v as_o many_o time_n as_o there_o be_v point_n in_o bc_n compose_v the_o rectangle_n abcd_v wherefore_o multiply_v ab_fw-la by_o bc_n i_o shall_v have_v the_o rectangle_n abcd._n as_o suppose_v i_o know_v the_o number_n of_o mathematical_a point_n there_o be_v in_o the_o line_n ab_fw-la for_o example_n let_v there_o be_v 40_o and_o that_o in_o bc_n
the_o line_n ab_fw-la bc_n you_o will_v have_v divide_v they_o equal_o and_o perpendicular_o by_o so_o do_v this_o be_v very_o necessary_a to_o describe_v astrolabe_fw-la and_o to_o complete_a circle_n of_o which_o we_o have_v but_o a_o part_n that_o astronomical_a proposition_n which_o teach_v to_o find_v the_o apogeum_n and_o the_o excentricity_n of_o the_o sun_n circle_n require_v this_o proposition_n we_o often_o make_v use_n there_o of_o in_o the_o treatise_n of_o cut_v of_o stone_n proposition_n xxvi_o theorem_fw-la the_o equal_a angle_n which_o be_v at_o the_o centre_n or_o at_o the_o circumference_n of_o equal_a circle_n have_v for_o base_a equal_a arks._n if_o the_o equal_a angle_n d_o and_o i_o be_v in_o the_o centre_n of_o equal_a circle_n abc_n efg_n the_o ark_n bc_n fg_v shall_v be_v equal_a for_o if_o the_o ark_n bc_n be_v great_a or_o lesser_a than_o the_o ark_n fg_v see_v that_o the_o ark_n be_v the_o measure_n of_o the_o angle_n the_o angle_n d_o will_v be_v great_a or_o lesser_a than_o the_o angle_n 1._o and_o if_o the_o equal_a angle_n a_o and_o e_o be_v in_o the_o circumference_n of_o the_o equal_a circle_n the_o angel_n d_o and_o i_o which_o be_v the_o double_a of_o the_o angle_n a_o and_o e_o be_v also_o equal_a the_o ark_n bc_n fg_v shall_v be_v also_o equal_a proposition_n xxvii_o theorem_fw-la the_o angle_n which_o be_v either_o in_o the_o centre_n or_o in_o the_o circumference_n of_o equal_a circle_n and_o which_o have_v equal_a ark_n for_o base_a be_v also_o equal_a if_o the_o angle_n d_o an_o i_o be_v in_o the_o centre_n of_o equal_a circle_n and_o if_o they_o have_v for_o base_a equal_a arcks_n bc_n fg_v they_o shall_v be_v equal_a because_o that_o their_o measure_n bc_n fg_v be_v equal_a and_o if_o the_o angle_n a_o and_o e_o be_v in_o the_o circumference_n of_o equal_a circle_n have_v for_o base_a equal_a ark_n bc_n eglantine_n the_o angle_n in_o the_o centre_n shall_v be_v equal_a and_o they_o be_v their_o half_n by_o the_o 20_o shall_v be_v also_o equal_a proposition_n xxviii_o theorem_fw-la equal_a line_n in_o equal_a circle_n correspond_v to_o equal_a arks._n if_o the_o line_n bc_n of_o be_v apply_v in_o equal_a circle_n abc_n def_n they_o shall_v be_v chord_n of_o equal_a ark_n bc_n ef._n draw_v the_o line_n ab_fw-la ac_fw-la de_fw-fr ef._n demonstration_n in_o the_o triangle_n abc_n def_n the_o side_n ab_fw-la ac_fw-la de_fw-fr of_o be_v equal_a be_v the_o semidiameters_a of_o equal_a circle_n the_o base_n bc_n of_o be_v suppose_v equal_a thence_o by_o the_o 8_o of_o the_o 1_o the_o angle_n a_o and_o d_o shall_v be_v equal_a and_o by_o the_o 16_o the_o ark_n bc_n of_o shall_v be_v also_o equal_a proposition_n xxix_o theorem_fw-la line_n which_o subtend_v equal_a arck_n in_o equal_a circle_n be_v equal_a if_o the_o line_n bc_n of_o subtend_v equal_a ark_n bc_n of_o in_o equal_a circle_n those_o line_n be_v equal_a demonstration_n the_o ark_n bc_n of_o be_v equal_a and_o part_n of_o equal_a circle_n therefore_o by_o the_o 27_o the_o angle_n a_o and_o d_o shall_v be_v equal_a so_o then_o in_o the_o triangle_n cab_n edf_n the_o side_n ab_fw-la ac_fw-la de_fw-fr df_n be_v equal_a as_o also_o the_o angle_n a_o and_o d_o the_o base_n bc_n of_o shall_v be_v equal_a by_o the_o 4_o of_o the_o 1_o use_v theodosius_n demonstrate_v by_o the_o 28_o and_o 29_o that_o the_o ark_n of_o the_o circle_n of_o the_o italian_a and_o babylonian_a hour_n comprehend_v between_o two_o parallel_n be_v equal_a we_o demonstrate_v also_o after_o the_o same_o manner_n that_o the_o ark_n of_o circle_n of_o astronomical_a hour_n comprehend_v between_o two_o parallel_n to_o the_o equator_fw-la be_v equal_a these_o proposition_n come_v almost_o continual_o in_o use_n in_o spherical_a trigonometry_n as_o also_o in_o gnomonic_n proposition_n xxx_o problem_n to_o divide_v a_o ark_n of_o a_o circle_n into_o two_o equal_a part_n it_o be_v propose_v to_o divide_v the_o ark_n aeb_fw-mi into_o two_o equal_a part_n put_v the_o foot_n of_o the_o compass_n in_o the_o point_n a_o make_v two_o ark_n f_o and_o g_o then_o transport_v the_o compass_n without_o open_v or_o shut_v it_o to_o the_o point_n b_o describe_v two_o ark_n cut_v the_o former_a in_o f_o and_o g_o the_o line_n gf_n will_v cut_v the_o ark_n ab_fw-la equal_o in_o the_o point_n e._n draw_v the_o line_n ab_fw-la demonstration_n you_o divide_v the_o line_n ab_fw-la equal_o by_o the_o construction_n for_o imagine_v the_o line_n of_o bf_n agnostus_n bg_n which_o i_o have_v not_o draw_v lest_o i_o shall_v imbroil_v the_o figure_n the_o triangle_n fga_n fgb_n have_v all_o their_o side_n equal_a so_o then_o by_o the_o 8_o of_o the_o 1_o the_o angles_n afd_v bfd_n be_v equal_a moreover_o the_o triangle_n dfa_n dfb_n have_v the_o sides_n df_n common_a the_o side_n of_o bf_n equal_a and_o the_o angles_n dfa_n dfb_n equal_a whence_o by_o the_o 4_o of_o the_o 1_o the_o base_n ad_fw-la db_fw-la be_v equal_a and_o the_o angles_n adf_n bdf_n be_v equal_a we_o have_v then_o divide_v the_o line_n ab_fw-la equal_o and_o perpendicular_o in_o the_o point_n d._n so_o then_o by_o the_o 1_o the_o centre_n of_o the_o circle_n be_v in_o the_o line_n eglantine_n let_v it_o be_v the_o point_n c_o and_o let_v be_v draw_v the_o line_n ca_n cb_n all_o the_o side_n of_o the_o triangle_n acd_v bcd_a be_v equal_a thence_o the_o angle_n acd_v bcd_a be_v equal_a by_o the_o 8_o of_o the_o 1_o and_o by_o the_o 27_o the_o ark_n ae_n ebb_n be_v equal_a use_v as_o we_o have_v often_o need_v to_o divide_v a_o ark_n in_o the_o middle_n the_o practice_n of_o this_o proposition_n be_v very_o ordinary_o in_o use_n it_o be_v by_o this_o mean_v we_o divide_v the_o mariner_n compass_n into_o 32_o rumb_n for_o have_v draw_v two_o diameter_n which_o cut_v each_o other_o at_o right_a angle_n we_o divide_v the_o circle_n in_o four_o and_o sub-dividing_a each_o quarter_n in_o the_o middle_n we_o have_v eight_o part_n and_o sub-dividing_a each_o part_n twice_o we_o come_v to_o thirty_o two_o part_n we_o have_v also_o occasion_n of_o the_o same_o practice_n to_o divide_v a_o semicircle_n into_o 180_o degree_n and_o because_o for_o the_o perform_v the_o same_o division_n throughout_o we_o be_v oblige_v to_o divide_v a_o ark_n into_o three_o all_o the_o ancient_a geometrician_n have_v endeavour_v to_o find_v a_o method_n to_o divide_v a_o angle_n or_o a_o ark_n into_o three_o equal_a part_n but_o it_o be_v not_o yet_o find_v proposition_n xxxi_o theorem_fw-la the_o angle_n which_o be_v in_o a_o semicircle_n be_v right_o that_o which_o be_v comprehend_v in_o a_o great_a segment_n be_v acute_a and_o that_o in_o a_o lesser_a segment_n be_v obtuse_a if_o the_o angle_n bac_n be_v in_o a_o semicircle_n i_o demonstrate_v that_o it_o be_v right_o draw_v the_o line_n da._n demonstration_n the_o angle_n adb_n exterior_a in_o respect_n of_o the_o triangle_n dac_n be_v equal_a by_o the_o 32d_o of_o the_o one_a to_o the_o two_o interiour_o dac_n dca_n and_o those_o be_v equal_a by_o the_o 5_o of_o the_o one_a see_v the_o side_n dam_fw-ge dc_o be_v equal_a it_o shall_v be_v double_a to_o the_o angle_n dac_n in_o like_a manner_n the_o angle_n adc_n be_v double_a to_o the_o angle_n dab_n therefore_o the_o two_o angel_n adb_n adc_fw-la which_o be_v equal_a to_o two_o right_a be_v double_a to_o the_o angle_n bac_n and_o by_o consequence_n the_o angle_n bac_n be_v a_o right_a angle_n second_o the_o angle_n aec_fw-la which_o be_v in_o the_o segment_n aec_fw-la be_v obtuse_a for_o in_o the_o quadrilateral_a abce_n the_o opposite_a angle_n e_z and_o b_o be_v equal_a to_o two_o right_v by_o the_o 22d_o the_o angle_n b_o be_v acute_a therefore_o the_o angle_n e_o shall_v be_v obtuse_a three_o the_o angle_n b_o which_o be_v in_o the_o segment_n abc_n great_a than_o a_o semicircle_n be_v acute_a see_v that_o in_o the_o triangle_n abc_n the_o angle_n bac_n be_v a_o right_a angle_n use_v 31._o use_v 31._o the_o workman_n have_v draw_v from_o this_o proposition_n the_o way_n of_o try_v if_o their_o square_n be_v exact_a for_o have_v draw_v a_o semicircle_n bad_a they_o apply_v the_o point_n a_o of_o their_o square_a bad_a on_o the_o circumference_n of_o the_o circle_n and_o one_o of_o its_o side_n ab_fw-la on_o the_o point_n b_o of_o the_o diameter_n the_o other_o side_n ad_fw-la must_v touch_v the_o other_o point_v d_o which_o be_v the_o other_o end_n of_o the_o diameter_n ptolemy_n make_v use_v of_o this_o proposition_n to_o make_v the_o table_n of_o subtendants_n or_o chord_n of_o which_o he_o have_v occasion_n in_o trigonometry_n 31._o use_v 31._o we_o have_v also_o a_o practical_a way_n to_o erect_v a_o perpendicular_a on_o the_o end_n of_o