The radius of a circle is 6.5. What is the diameter, circumference, and area?

See solution below

Diameter:

The diameter is always double the length of the radius.

Assuming d represents diameter:

d = 6.5(2)

d = 13

The diameter of the circle measures 13.

Circumference

The formula for circumference of a circle is dπ, where d is diameter and π is pi.

Now that we know the length of the diameter, we can find the circumference, or distance around the circle.

Assuming that C represents circumference

C = dπ C = 13π C = 13π or 40.84

The circumference measures 13π (exact value) or 40.84 (rounded to the nearest hundredth).

Area

The formula for area is A = ##r^2##π. The radius measures 6.5, so we have enough information to solve for A

A = ##r^2##π A = ##6.5^2##π A = 42.25π or 132.73

The area is 42.25π ##units^2## or 132.73 ##units^2##

Hopefully you understand some of the characteristics of circles now!