If `sec(theta+alpha)+sec(theta-alpha)=2sectheta` then show that `cos^2theta=1+cosalpha`

If sec(theta+alpha)+sec(theta-alpha)=2sec theta then show that cos^(2)theta=1+cos alpha

If sec(theta+alpha)+sec(theta-alpha)=2sec theta, prove that cos theta=+-sqrt(2)(cos alpha)/(2)

If sec(theta+alpha)+sec(theta-alpha)=2\ s e ctheta, prove that costheta=+-sqrt(2)cosalpha/2dot

If sec(theta +alpha)+sec(theta-alpha = 2sectheta, costheta is equal to :

If sec(theta+alpha)+sec(theta-alpha)=2/costheta . then cos^2theta is equal to

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

sqrt(sec^2theta-1)/(sectheta)

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

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

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