Parts of a Circle & Circumference

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

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

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

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

5. 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

6. 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

7. 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 3.14 3.14 12.00 in ≈ d