Question

Find the volume of the solid obtained by rotating the region bounded by the curves y=cos⁡(x), y=0, x=0, and x=π/2 about the line y=1.

Answer 1

The problem is faulty: it gives you only one boundary of the region and leaves you to guess about the others.

$Volume = 2π\int^{2π}_0 (1-cosx)\\ = 2π[x-sinx]^{2π}_0\\ = 2π(2π- 0) \\ = 4π²$