What is the area of a circle whose radius is 4 cm?

Well first, we must remember the formula for the area of a circle.
The formula for the area of a circle is:
PiR^2, or Pi • R^2.
Basically this means 3.14 (Pi) • R • R (Radius).
We have our radius, 4, so we can plug in our numbers to solve.
3.14 • 4 • 4 is our formula, so let's solve.
4 • 4 = 16.
16 • 3.14 = 50.24.

Remember when we solve for the area, we use units squared (units^2).

Your answer is 50.24 cm^2.

I hope this helps!