Alan measures the circular floor of a tepee, then calculates that it has an area of 12.56 square yards. What is the floor's diameter?

Use 3.14 for pi.

[ ] yards

The area of a circle is found by pi*r^2

We can plug in the values we know to solve for the radius.

12.56 = 3.14*r^2

Divide both sides by pi.

12.56/3.14 = r^2

Square root both sides.

r = 2 yards

The diameter of a circle is twice as long as the radius, so the answer is 4 yards.