Question

Чему равен sin3x? Срочно

Answer 1

Sin 3x=Sin(2x+x)= Sin2xCosx + Cos2xSinx = 2SinxCosxCosx+
(Cos^2 x - sin^2 x) Sinx = 2SinxCos^2 x + Cos^2 xSinx- Sin^3 x=3SinxCos^2 x - Sin^3 x.
Sin3x = 3SinxCos^2 x - Sin^3 x