If `sec(theta+alpha)+sec(theta-alpha)=2sec theta` and `cos alpha!=1`, prove that `cos theta=+-sqrt"cos"(alpha)/2`

If sec ( theta - alpha ) , sec theta , sec ( theta + alpha ) are in A.P. then cos theta =

If sin ( theta + alpha ) = cos ( theta + alpha ) , then tan theta =

If sec ( theta + alpha ) , sec theta , sec (theta - alpha ) are in A.P. Then cos theta sec alpha //2=

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

cos ( theta + alpha)* cos ( theta - alpha) + sin ( theta + alpha) * sin (theta - alpha )=

If cos(theta - alpha)=a, cos(theta-beta)=b , then sin^(2)(alpha -beta) + 2abcos(alpha-beta)=0

If sin alpha cos h beta = cos theta and cos alpha sin h beta= sin theta , then prove that sinh^(2)beta= cos^(2)alpha .

sec h^(-1) (cos theta) =