Question

The distance around a circle and the distance across a circle are related.



C. What do you notice about the ratio of the distance around the circle to the distance across the circle for each circle?

A CD, a button and a dartboard are shown.

Answer 1

The ratio of the distance around a circle (circumference C) to the distance across it (diameter d) is the same for each circle. That common value is π (pi), about 3.1416. In formula form: C = πd, so C/d = π. (In real measurements you may get slight differences from 3.14 because of measurement error.)