If `cos(theta+phi) cos theta and cos(theta+phi) ` are in harmonic progression then `cos theta sec"" (phi)/(2)` is :

i) sec(theta) = cos(theta)

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

If sintheta=5sin(theta+phi) then tan(theta+phi)=

Solve: cos5theta=cos2theta

If cos(theta+phi)=mcos(theta-phi) then tantheta is equal to

Solve cos theta+cos 2theta+cos 3theta=0 .

Solve: cos2theta=cos^(2)theta

Suppose theta and phi(ne 0) are such that sec (theta+phi), sec theta and sec (theta-phi) are in A.P. If cos theta=kcos((phi)/(2)) for some k, then k is equal to

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

Prove that : sec theta + cos theta != 3/2