Question

how to integrate cos^3(x)cos(2x)?

Answer 1

\[\cos(2x)=2\cos^2(x)-1\]

Answer 2

@Zarkon better way would be converting cos^3(x) to cos 3x

Answer 3

but \[\cos^3(x)\ne\cos(3x)\]

Answer 4

\[\cos^3x=\frac{\cos3x+3cosx}{4}\]
It is lot easier to convert compound angles to integrable forms than powers of trigonometric exponents

Answer 5

do you have general form?

Answer 6

some one along the line forgot to invent genral formulas for integration