Sin³a cosa-sina cos³a

Question

Sin³a cosa-sina cos³a

Answer 1

Sin³α*cosα-sinα*cos²α=-sinα*cosα*(cos²α-sin²α)=
=-(1/2)*2sinα*cosα*(cos²α-sin²α)=-(1/2)*sin2α*cos2α=-(1/2)*(1/2)*2sin2α*cos2α=-(1/4)sin4α=-0,25*sin4α