Product-to-sum identities for JEE

Formula

\[\sin A\sin B=\frac{1}{2}\big[\cos(A-B)-\cos(A+B)\big]\] \[\cos A\cos B=\frac{1}{2}\big[\cos(A-B)+\cos(A+B)\big]\] \[\sin A\cos B=\frac{1}{2}\big[\sin(A+B)+\sin(A-B)\big]\]

Variables: \(A,B\) are angles/expressions.

Integration of trigonometric products.