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. 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)=

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 costhetasec(alpha//2) is equal to

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