volume of solid bounded by the graph of y = cos(x), the x−axis, and the y− axis over the interval [0, π/4] is revolved about the x-axis

I need to know what formula to use I know how to solve integrals so I don't need the whole thing done but i just need to know how to set it up.

this is what I did:

the integral of 2πx(cosx)dx from 0,π/4

Thanks!

V = pi * integral (from 0 to pi/4) of (cos(x))^2 dx

and in general the volume of a solid when function f(x) is revolved around x axis is

V = pi * integral (from a to b) of (f(x))^2 dx