Question

Prove that sin θ - sin θ•cos2 θ = sin3 θ. Show all works of the equation.

Answer 1

I used x instead of Ф.


`sinx- (cos x)^(2) *sinx= (sin x)^(3)`


`sinx(1-(cos x)^(2))=(sin x)^(3)`

You use the fundamental formula sin^2x+cos^2x=1

sinx*sin^2x=sin^3x
sin^3x=sin^3x