2. Diameter  Any line segment that passes through the center of the circle and has endpoints on the circle.

3. Diameter  A line segment that connects the center of the circle with any point on the circle. TThe radius is equal to half of the diameter.

4. Diameter

5.  Circumference is the distance around a circle.  Think of it like the perimeter of a circle.  If we know the diameter of a circle we can use the formula C = d to find the circumference.

6. Diameter

7.  This is the amount of surface inside of a circle.  If we know the radius of the circle we can determine the area of the circle using the formula A = r 2

8. 3 cm What is the radius of this circle? What is the Diameter? Use the formula ______ to find the circumference. Use the formula ______ to find the area.

9. 12 m What is the radius of this circle? What is the Diameter? Use the formula ______ to find the circumference. Use the formula ______ to find the area.

10. 8 m What is the radius of this circle? What is the Diameter? Use the formula ______ to find the circumference. Use the formula ______ to find the area.

11. 7 cm What is the radius of this circle? What is the Diameter? Use the formula ______ to find the circumference. Use the formula ______ to find the area.

12. 11 cm 18cm d = r = C = A = d = r = C = A =

13. Diameter For dinner on Friday, you called Nochinno’s asking what their special was that evening. The clerk told you could order a pizza with a diameter of 10in for $9.99 or you could order two 6in pizzas for the same price. Which is the better deal?