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If cos alpha =(3)/(5) and cos beta =(5)/...

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)`

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