Question

A= 4 πr^2 solve for R

Answer 1

Answer:

$r = \pm\sqrt{\frac{A}{4 \pi}}$

Step-by-step explanation:

Given:

The given equation is $A = 4 \pi r^{2}$

We need to solve the given equation for r.

Rewrite the equation as.

$4 \pi r^{2}=A$

Divide both side of the equation by 4π and simplify

$\frac{4 \pi r^{2}}{4 \pi}=\frac{A}{4 \pi}$

$r^{2}=\frac{A}{4 \pi}$

Take the square root both side of the equation.

$\sqrt{r^{2} } = \sqrt{\frac{A}{4 \pi}}$

$r = \pm\sqrt{\frac{A}{4 \pi}}$

Therefore, the solution for r is both positive or negative  $r = \pm\sqrt{\frac{A}{4 \pi}}$