Sin^3 a (1+ctga)+cos^3(1+tga)

Question

Sin^3 a (1+ctga)+cos^3(1+tga)

Answer 1

Sin^3a(1+ctga)+cos^3a*(1+tga)=(1+cosa/sina)sin^3a+cos^3a(1+sina/cosa)=
=(sina+cosa)(sin^2a+cos^2a).