Can anyone help me solve this calculus problem?

Question

Find the volume generated by revolving the region about the x-axis.

 y = (2cosx) 0 ≤ x ≤ π,  x = 0,    y = 0

Answer 1

Let V= π∫₀^π/2y²dx where y=√(2cosx). So y² = 2cosx and the integral becomes V=π•2sinx |₀^π/2 =2π