Integrate sin7xcos3x

Let A=7x and B=3x( From the formulae we know that sinxcosx= 1/2(sin(A+B)+sin(A-B))So if we replace A=7x and B=3x in this equation: 1/2(sin(7x+3x)+sin(7x-3x))= = 1/2 (sin(10x)+sin(4x))Now we just integrate 1/2(sin(10x)+sin(4x)), which will give the answer: -cos(10x)/20-cos(4x)/8+C