Factors of `cos4theta-cos4phi` are

Factors of cos4 theta-cos4 phi are

A factor of cos 4theta - cos 4phi is

The value of ((sin theta + sin phi)/(cos theta + cos phi)+ (cos theta - cos phi)/(sin theta - sin phi)) is :

If cos(theta-phi) , cos(theta) , cos(theta+phi) are in HP, the the value of cos(theta)sec(phi/2) is

If the sides of a triangle are in A.P. and the greater and the least angles are theta and phi respectively, then show that, 4(1-cos theta)(1-cos phi) = cos theta +cos phi

Prove that : cos (pi/4- theta)cos (pi/4-phi)-sin(pi/4-theta) sin (pi/4-phi)= sin (theta+phi) .

The sides of triangle are in A.P. and the greatet and least angle are theta and phi: prove that 4(1-cos theta)(1-cos phi)=cos theta+cos phi

If cos theta+cos phi=a and sin theta - sin phi=b , then: 2cos(theta + phi) =