Найдите cos2a и sin2a если cosa=-3\5,

cos2a = 2cos^2a - 1 = 2(-3/5)^2 - 1 = 2(9/25) - 1 = 18/25 - 1 = -7/25 sin2a = 2sinacosa = 2(-3/5)*(-4/5) = 24/25

Ответ: cos2a = -7/25, sin2a = 24/25