Prove that `sin^2theta

Prove that sin^2 theta+sin^2 2theta+sin^2 3theta+....+sin^2 n theta=n/2-(sin n theta cos(n+1)theta)/(2sin theta)

Prove that sin^2(theta-phi)-sin^2(theta+phi)= -sin2theta sin2phi hence prove that cos2thetacos2phi-sin^2(theta+phi)+sin^2(theta-phi)=cos(2theta+2phi)

Prove that sin^(2)theta+cos ec^(2)theta>=2

Prove that, sin^2 theta+ cosec^2 theta>=2

Prove that: (sin2theta)/(1+cos2theta)=t a ntheta

Prove that: (sin2theta)/(1-cos2theta)=cottheta

Prove that: (sin2theta)/(1+cos2theta)=t a ntheta

Prove that (sin2theta)/(1+cos2theta)=tantheta

Prove that (sin2theta)/(1-cos2theta)=cottheta

Prove that: (sin2theta)/(1+cos2theta)=tantheta