If `cos 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=28/65.

If sin 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+ cos beta =1/3 and sin alpha+sin beta=1/4 prove that cos[(alpha-beta)/2] =+-(5/24)

if cos alpha=(3)/(5) and cos beta=(4)/(5) find the value of cos((alpha-beta)/(2))

If coa alpha+cos beta=(1)/(3) and sin alpha+sin beta prove that cos((alpha-beta)/(2))=+-(5)/(24)

Let alpha, beta be such that pi lt alpha lt beta lt 3pi, if sin alpha + sin beta =- (21)/(65) and cos alpha + cos beta =(27)/(65), then the value of cos ""(alpha - beta)/(2) is-

If alpha, beta be such that pi < alpha- beta < 3 pi . If sin alpha +sin beta= -21/65 and cos alpha + cos beta = -27/65 , then the value of cos frac (alpha-beta)(2) is :