Question

Make r subject of the formula Formula1" title="s = 4\pi \: r {}^{2} " alt="s = 4\pi \: r {}^{2} " align="absmiddle" class="latex-formula">
​

Answer 1

Answer:

r = √( s/4π)

Step-by-step explanation:

s = 4πr²

s/4π = 4πr²/4π

r² = s/4π

√(r²) =+/-√( s/4π)

r = √( s/4π)     Because r is a radius of the circle , it should be positive.

Answer 2

Answer:

$\boxed{r = \pm \frac{ \sqrt{s} }{2 \sqrt{\pi} } }$

Step-by-step explanation:

$Solve \: for \: r: \\ = > s=4\pi {r}^{2} \\ \\ s =4\pi {r}^{2} \: is \: equivalent \: to \: 4\pi {r}^{2} = s: \\ = > 4\pi {r}^{2} =s \\ \\ Divide \: both \: sides \: by \: 4\pi: \\ {r}^{2} = \frac{s}{4\pi} \\ \\ Take \: the \: square \: root \: of \: both \: sides: \\ = > r = \frac{ \sqrt{s} }{2 \sqrt{\pi} } \: \: \: \: or \: \: \: \: r = - \frac{ \sqrt{s} }{2 \sqrt{\pi} }$