Question

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

4 cm

12 cm

30 cm

Answer 1

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