Prove that `cos 2 theta cos 2 phi + sin ^(2) ( theta - phi) -sin ^(2) (theta + phi) = cos ( 2 theta + 2 phi).`

(sin (theta + phi))/( sin theta cos phi) = cot theta tan phi +1.

cos2thetacos2phi+sin^2(theta-phi)-sin^2(theta+phi)=

(sin ( theta -phi))/(sin theta sin phi) = cot phi - cot theta.

Prove that (1 - cos 2 theta)/( sin 2 theta) = tan theta.

Prove that cos^2 theta cosec theta+sin theta=cosec theta

Prove that : (cos 4theta + cos 3theta + cos 2theta)/(sin 4theta + sin 3theta + sin 2theta) = cot 3theta

Prove that (cos theta+sin theta )^2 + (cos theta - sin theta )^2 =2

Prove that cos theta cos 2 theta cos 4 theta…. Cos 2 ^(n-1) theta = ( sin ( 2 ^(n) theta))/( 2 ^(n) (sin theta)) .

"cos"2theta."cos"2phi+"sin"^(2)(theta-phi)-"sin"^(2)(theta+phi) is equal to (i) "sin"2(theta+phi) (ii) "cos"2(theta+phi) (iii) "sin"2(theta-phi) (iv) "cos"2(theta-phi)

If 0 lt theta , phi lt pi and 8 cos theta cos phi cos (theta + phi)+1=0 find theta and phi