Area of a Circle: Calculate The Missing Side based on the formula

A circle has an area of 25 cm².

What is its radius?

Area of the circle:

$S=\pi r^2$

We insert the known data:

$25=\pi r^2$

Divide by Pi:$\frac{25}{\pi}=r^2$

Extract the root:$\sqrt{\frac{25}{\pi}}=r$

$\frac{5}{\sqrt{\pi}}=r$

$\frac{5}{\sqrt{\pi}}$ cm

Look at the circle in the figure.

What is the diameter of the circle?

14 cm

Look at the circle in the figure below.

What is the radius of the circle?

3 cm