263put the values of a and b to get the answer
ARKADYUTI BANDYOPADHYAY I have tried. It does not work.Upvote·0· Reply ·2014-07-17 06:08:18
If sin α + sin β = a and cos α + cos β = b,then prove that sin(α + β) = (2ab/a2 + b2)
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263
146the best method is by using transformation of sums and products
by using that a=2sin(α+β)/2 *cos(α-β)/2-(1) and for b=2cos(α+β)/2 *cos(α-β)/2-(2)
now dividing (1) by (2) we get tan(α+β)/2=a/b
now simply using the formula of sin2θ=2tanθ/1+tan^2θ the identity will be proved