Find the volume of the solid obtained by revolving y=3-x and y=2*x^0.5 about the x-axis.
Determine if the statements are true and explain why.
1. A pyramid is a solid of revolution.
2. The volume of a sphere can be computed using the disk method.
3. Let R1 be the region bounded by y=cosx and the x-axis on [-pi/2, pi/2]. Let R2 be the region bounded by y=sinx and the x-axis on [0, pi]. The volumes of the solids generated when R1 and R2 are revolved about the x-axis are equal.