Question

The height of a square based pyramid of volume $300$c.c is $10$cm. Find the edge of the base.

Answer 1

The general formula for volume of pyramid is $V=\frac{1}{3}Bh$ where $B$ is the area of the base and $h$ is the height.

Since the volume of the pyramid is $V=300$ cm${}^3$ and the height $h=10$ m, therefore, the edge of the base is:

$V=\frac{1}{3}Bh\Rightarrow V=\frac{1}{3}{s}^{2}h\Rightarrow 300=\frac{10}{3}{s}^2\Rightarrow s^2=\frac{900}{10}=90\Rightarrow s=\sqrt{90}=3\sqrt{10}$

Hence, the edge of the base is $3\sqrt{10}$ cm.