Question

решить уравнение
4sin^3x.cos3x+4cos^3x.sin3x
= 3sin2x​

Answer 1

sin3x = sin(2x + x) = sin2x cosx + cos2x sinx =
=2sinx cosx cosx + (1-2sin^2 x)sinx = 2sinx (1-sin^2 x) + sinx - 2sin^3 x =
= 2sinx - 2sin^3 x + sinx -2sin^3 x = 3sinx - 4sin^3 x