Question

Rearrange the formula A = π(R2 − r2) for R.

Answer 1

If you are doing it on USATestPrep, the answer is

D) R= Square root of A over \pi and plus r^2

The Square root goes all the way

I hope this helped ;)

Answer 2

ANSWER


`R = \pm \sqrt{(A+\pi r^2)/( \pi)}`

Step-by-step explanation

We want to rearrange the formula,


`A=\pi(R^2-r^2)`
for

`R.`

This means that, we will isolate

`R`
so that, it will be on one side of the equation, while the others are also on the other side of the equation.

We must first divide through by π to obtain,


`(A)/( \pi) =R^2-r^2`

We add

`{r}^(2)`

to both sides to obtain,


`(A)/( \pi) + {r}^(2) =R^2`

We now take the square root of both sides to obtain,


`\pm \sqrt{(A)/( \pi) + {r}^(2)} =R`

We simplify further to obtain,


`R = \pm \sqrt{(A+\pi r^2)/( \pi)}`