Найдите ѕina и cosa, если tgа
=5/12
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sina = +-12/13, cosa = +-5/13

Объяснение:

1/sin^2a= tg2a + 1

1 / sin^2a = (5/12)^2 + 1

1 / sin^2a = 25/144 + 1

sin^2a = 144/169

(sina > 0) sina = 12/13

(sin < 0) sina = -12/13

sina = +-12/13

1/cos^2a = ctg^2a + 1

1 / cos^2a = 144/25 + 1(тк ctga = 1/tga)

1 / cos^2a = 169/25

(cosa > 0) cosa = 5/13

(cosa < 0) cosa =-5/13

cosa = +-5/13