Look at the formula for the area of a circle below. A = r2Which of the following equations can be used to solve for the radius (r)?

Question

Look at the formula for the area of a circle below. A  =   r2Which of the following equations can be used to solve for the radius (r)?

solomonzelman · Answer

the formula for the area of the circle is $A=\pi {\rm r}^2$
(you left out $\pi$ there)

solomonzelman · Answer

1)   divide by $\pi$ on both sides
2)   square root both sides
3)   normally when you do square roots you include $\pm$  sign next to it, but in this case, since radius of the circle can be only positive (and not negative), you would not include the negative solution.