If `cosalpha=3/5` and `cosbeta=5/13` then `cos^2((alpha+beta)/2)=16/65`

If cos alpha=4/5 and cos beta =5/13, prove that cos (alpha-beta)/2=28/65.

If sin alpha=4/5 and cos beta =5/13, prove that cos ((alpha-beta)/2)=8/sqrt 65.

If cos alpha=(4)/(5) and cos beta=(5)/(13), prove that (cos(alpha-beta))/(2)=(8)/(sqrt(65))

If cos alpha=(3)/(5) and cos beta=(5)/(13), then cos^(2)backslash(alpha-beta)/(2)=

If cos alpha = (3)/(5) , cos beta =(5)/(13) , "then " cos^(2) ((alpha - beta )/(2))=

If cos alpha=3/5 and cos beta = 5/13 and alpha , beta are acute angles , then prove that cos^(2)((alpha+beta)/2)=16/65

If cos alpha =(3)/(5) and cos beta =(5)/(13) and alpha, beta are acute angles, then prove that (a) sin ^(2)((alpha-beta)/(2))=(1)/(65) and (b) cos ^(2)((alpha+beta)/(2))=(16)/(65)

If cosalpha=1/2(x+1/x) cosbeta=1/2(y+1/y) then cos(alpha-beta) is equal to

Let alpha,beta be such that pi<(alpha-beta)<3pi . If sinalpha+sinbeta=-21/65 and cosalpha+cosbeta=-27/65 , then the value of cos((alpha-beta)/2) is

If cosalpha+cosbeta=0=sinalpha+sinbeta" then "cos2alpha+cos2beta