Circumference and Radius

This 12-question quiz works through the parts of a circle and the formulas that connect them.

You will identify relationships and run calculations with items like What is the formula for finding the circumference of a circle? and The radius of a circle is 6 cm. What is the diameter?

The handle on all of it is the value of pi, roughly 3.14, which links a circle's distance around to the distance straight across.

Once you remember that the diameter is simply twice the radius, the rest of the formulas tend to fall into place.

Recommended level: intermediate.