f(sin x) = 2sin^2 x + 3sin x - 2 = (2sin^2 x - 2) + 3sin x = 3sin x - 2cos^2 x
пояснение:
так как sin^2 + cos^2 = 1, то:
2sin^2 x + 2cos^2 x = 2 => 2sin^2x - 2 = -2cos^2 x
