cottheta+tan^3thetacotθ+tan3θ
=costheta/sintheta+sin^3theta/cos^3theta=cosθsinθ+sin3θcos3θ
=(cos^4theta+sin^4theta)/(sintheta*cos^3theta=cos4θ+sin4θsinθ⋅cos3θ
=((cos^2theta+sin^2theta)^2-2sin^2thetacos^2theta)/(sintheta(1-sin^2theta)^(3/2)=(cos2θ+sin2θ)2−2sin2θcos2θsinθ(1−sin2θ)32
=(1-2sin^2theta(1-sin^2theta))/(sintheta(1-sin^2theta)^(3/2)=1−2sin2θ(1−sin2θ)sinθ(1−sin2θ)32