Prove that:
(i) 1sin(x−a)sin(x−b)=cot(x−a)−cot(x−b)sin(a−b)
(ii) 1sin(x−a)cos(x−b)=cot(x−a)+tan(x−b)cos(a−b)
=1sin(a−b)=1sin(a−b)[sin(x−b)−(x−a)cos(x−a)cos(x−b)]=1sin(a−b)=[sin(x−b)cos(x−a)−cos(x−b)sin(x−a)cos(x−a)cos(x−b)cos(x−a)cos(x−b)]=1sin(a−b)[sin(x−b)cos(x−b)−sin(x−a)cos(x−a)]=1sin(a−b)[tan(x−b)−tan(x−s)]=tan(x−b)−tan(x−a)sin(a−b)
= RHS
∴ LHS = RHS Hence proved.