If `cos(theta-alpha),cos(theta),cos(theta+alpha)` are in H.P. then `costheta.secalpha/2

If cos(theta-alpha),costheta,cos(theta+alpha) are in H.P.,then costhetasec(alpha//2) is equal to

If cos(theta - alpha) , costheta , cos(theta + alpha) are in H.P. then costheta.sec(alpha/2) =

If cos(theta - alpha) , costheta , cos(theta + alpha) are in H.P. then costheta.sec(alpha)/2 =

If cos (theta - alpha),cos(theta),Cos(theta + alpha) are in H.P. and cos alpha ne 1 , then angle alpha lie in the

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

If cos^4 theta sec^2 alpha,1/2 and sin^4 theta cosec^2 alpha are in A.P. , then cos^8 theta sec^6 alpha ,1/2 and sin^8 theta cosec^6 alpha are

Prove that cos 4theta–cos 4alpha = 8(cos theta-cos alpha)(cos theta+ cos alpha )(cos theta -sin alpha)(cos theta+sin alpha)

The value of the determinant |{:(cos(theta+alpha),-sin(theta+alpha),cos2alpha),(sintheta,costheta,sinalpha),(-costheta,sintheta,lambdacosalpha):}| is

Simplify be reducing to a single term : cos (theta + alpha ) cos ( theta - alpha ) - sin ( theta + alpha ) sin (theta - alpha).

If ( sin ^(3) theta)/( sin ( 2theta+ alpha )) = ( cos ^(3) theta)/( cos ( 2 theta + alpha)) and tan 2 theta = lamda tan ( 3theta + alpha) then the value of lamda is ____________.