Question

Очень надо, помогите плиз
2sin(pi - a)cos(pi/2 - a) + 3sin^2(pi/2 - a) - 2

Answer 1

2sin(pi - a)cos(pi/2 - a) + 3sin^2(pi/2 - a) - 2 = 2sinαsinα + 3cos²α - 2 =
= 2sin²α - 2 + 3cos²α = -2(1 - sin²α) + 3cos²α = - 2cos²α + 3cos²α = cos²α