Find the volume V of the described solid S.
a.A right circular cone with height 6h and base radius 3r
b.The base of S is the triangular region with vertices (0, 0), (4, 0), and (0, 4). Cross-sections perpendicular to the y-axis are equilateral triangles.
c.The base of S is the region enclosed by the parabola y = 5 - 2x2 and the x-axis. Cross-sections perpendicular to the y-axis are squares.