Solve piR^2=28.26

$$\pi R ^ { 2 } = 28.26$$

Solve for R

$$R = \frac{3 \sqrt{\frac{314}{\pi}}}{10} \approx 2.999239468$$

$$R = -\frac{3 \sqrt{\frac{314}{\pi}}}{10} \approx -2.999239468$$

Steps by Finding Square Root

Divide both sides by \pi .

$$\frac{\pi R^{2}}{\pi }=\frac{28.26}{\pi }$$

Dividing by \pi undoes the multiplication by \pi .

$$R^{2}=\frac{28.26}{\pi }$$

Divide 28.26 by \pi .

$$R^{2}=\frac{1413}{50\pi }$$

Take the square root of both sides of the equation.

$$R=\frac{471}{5\sqrt{314\pi }} R=-\frac{471}{5\sqrt{314\pi }}$$

Steps Using the Quadratic Formula

Subtract 28.26 from both sides.

$$\pi R^{2}-28.26=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute \pi for a, 0 for b, and -28.26 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$R=\frac{0±\sqrt{0^{2}-4\pi \left(-28.26\right)}}{2\pi }$$

Square 0.

$$R=\frac{0±\sqrt{-4\pi \left(-28.26\right)}}{2\pi }$$

Multiply -4 times \pi .

$$R=\frac{0±\sqrt{\left(-4\pi \right)\left(-28.26\right)}}{2\pi }$$

Multiply -4\pi times -28.26.

$$R=\frac{0±\sqrt{\frac{2826\pi }{25}}}{2\pi }$$

Take the square root of \frac{2826\pi }{25}.

$$R=\frac{0±\frac{3\sqrt{314\pi }}{5}}{2\pi }$$

Now solve the equation R=\frac{0±\frac{3\sqrt{314\pi }}{5}}{2\pi } when ± is plus.

$$R=\frac{471}{5\sqrt{314\pi }}$$

Now solve the equation R=\frac{0±\frac{3\sqrt{314\pi }}{5}}{2\pi } when ± is minus.

$$R=-\frac{471}{5\sqrt{314\pi }}$$

The equation is now solved.

$$R=\frac{471}{5\sqrt{314\pi }} R=-\frac{471}{5\sqrt{314\pi }}$$