Question

If $V=\pi r^{2}h$, then solve for '$r$' and find the value of '$f$' when $V=176$ and $h=14$.

Answer 1

Given $V=\pi r^{2}h$
$\pi r^{2}h=V,\therefore r^2=\frac{V}{\pi h}$
$\therefore r=\pm \sqrt{\frac{V}{\pi h}}$
If V = 176 and h = 14, we get
$r=\pm \sqrt{\frac{176}{\pi \times 14}}$ (by substituting the values) $\therefore r=\pm \sqrt{\frac{176\times 7}{22\times 14}}=\pm \sqrt{\frac{8}{2}}=\pm \sqrt{4}=\pm 2$
$\therefore r=+2$ or $r=-2$