(1) sin75°+sin15° @ sin75°—sin15° @ cos75°+cos15° @ cos75°—cos15°

@ : sin75°+sin15°=2sin(2 _ jeas( 2 mal 2 2 2

@ : sin75°—sin15°=2cos( 15 Poe )sin( 2S ) 2 1/2 2 23 2

@ : cos75°+cos15°= Se ce ee

2 =2ㆍ 12 . 19 _ 16 2 2 2 @ : 00675 00815 = oa +15” \s aoe

sta 크

= 12 . 1 5

프톨레마이오스가 들려주는 삼각비 2 이야기