Adding the given relation , we get
ab+AB=sin(x−α+x−β)sin(x−β)cos(x−β)
aB+bAbB=sin(2x−α−β)sin(x−β)cos(x−β)
Multiplying the given relation and adding 1 , we get
aAbB+1=sin(x−α)cos(x−α)+sin(x−β)cos(x−β)sin(x−β)cos(x−β)
or aA+bBbB
=12⋅sin(2x−2α)+sin(2x−2β)sin(x−β)cos(x−β)
=12⋅2sin(2x−α−β)cos(α−β)sin(x−β)cos(x−β)
Dividing (1) and (2) ,we get result