This is the third section of "Chapter 5: Measurement of Circles". We skipped section 5.2, since we covered all the relevant material when we did section 5.1, "Exploring Circles".

Relationships Between Circumference, Diameter and Radius

There are three relationships that students can use to solve problems.

• The diameter is twice the radius: $latex d = 2r$
• The circumference is pi times the diameter: $latex C = \pi d$ and
• The circumference is 2 times pi times the radius: $latex C = 2 \pi r$.