Question

Find the height of a right circular cone whose radius is 5 cm and volume is 100π cm3.

Answer 1

$V=\dfrac{1}{3}\pi r^2H\\\\V=100\pi\ cm^3;\ r=5\ cm\\\\subtitute\\\\\dfrac{1}{3}\pi\cdot5^2\cdot H=100\pi\ \ \ |divide\ both\ sides\ by\ \pi\\\\\dfrac{1}{3}\cdot25H=100\ \ \ |multiply\ both\ sides\ by\ 3\\\\25H=300\ \ \ \ |divide\ both\ sides\ by\ 25\\\\\boxed{H=12\ (cm)}$