1. By: Kay McInnis

2. Diameter DIAMETER is the distance across a circle passing through the center point.

3. Radius RADIUS is the distance from the center to any point on the circle.

4. Diameter Radius Can you identify the relationship between the DIAMETER and the RADIUS of a circle?

5. Diameter The RADIUS is half of the DIAMETER. Radius

6. CIRCUMFERENCE CIRCUMFERENCE is the distance around the circle.

7. CIRCUMFERENCE The relationship between the DIAMETER and the CIRCUMFERENCE of a circle is PI. DIAMETER

8.  The symbol for PI is . The value of PI is 3.14.

9. To find the CIRCUMFERENCE of a circle, multiply the DIAMETER and PI. C = d x 

10. d = 5 m Can you figure out the CIRCUMFERENCE of the circle? If d = 5 and  = 3.14, then CIRCUMFERENCE equals 5 x 3.14. C = 15.7 m

11. d = 10 cm Find the CIRCUMFERENCE of the circle. 10 x 3.14 = C C = 31.4 cm