Solve ∫sin(x+a)sin(x+b)dx
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)
Prove that SinA+sinB=sin(A+B)cos(A+B)/2