2. Parts of a Circle & Circumference Textbook page 516 IAN page 120

3. Circumference Diameter The circumference of a circle is the distance around the outside of a circle The diameter of the circle is the distance from one side to the other passing through the centre of the circle What is circumference? What is diameter?

4. Radius Chord A chord is a line touching the circumference of the circle at two points The radius is the line connecting the centre of the circle and the circumference What is a chord? What is a radius?

5. Example 1: Name the circle, diameter, and three radii. C AB O The circle is circle O AB is the diameter OA, OB, and OC are radii

6. Example 2: Find each missing value to the nearest hundredth. Use 3.14 for pi. (A) d = 8 ft; C = ? C = πd C ≈ 3.14. 8 C ≈ 25.14 ft 8 ft

7. Example 2: Find each missing value to the nearest hundredth. Use 3.14 for pi. (B) r = 3 cm; C = ? C = 2πr C ≈ 2. 3.14. 3 C ≈ 18.84 cm 3 cm

8. Example 2: Find each missing value to the nearest hundredth. Use 3.14 for pi. (C) C = 37.68 in; d = ? C = πd 37.68 ≈ 3.14. d 37.68 ≈ 3.14 d 3.143.14 12.00 in ≈ d