Brain trainer

1. What are some words you remember that go with circle? Get out 5 pieces of paper and fold like a hamburger. Brain trainer

2. Standards G.6.1, G.6.2, G.6.7 Lesson 10-1: Circles and Circumferences

3. A Circle is the shape that is produced when you plot all of the points which are the same distance away from a center point. What is a Circle? Circles are referred to by the center point. This circle would be called ๏E E

4. Chord – Any line segment drawn inside a circle. This is chord AB. A chord always touches 2 edges of the circle. Radius – Any line segment drawn from the center to a point on the circle. This is radius DC C A X Y Diameter – Any chord which runs through the center of the circle. This is diameter XY. Center B Parts of Circles D Notice: A radius is always half of a circle’s diameter

5. Circumference • The perimeter of a circle is called its circumference • Formula: C = 2pr (or dp) • p ≈ 3.14 r = the circle’s radius Note: You may leave a circumference answer in terms of p unless you are asked for a decimal approximation.

6. Find mQT Find mUY Find mQY Name a radius Name a diameter Name a chord Name this circle Find the circumference Example U T 10 W 20 10 10 Q QW, QU, QT, QY UY X Z XZ, UY Y ๏ Q 20p 2p (10)

7. You Try This One The diameters of ๏X, ๏Y, and ๏Z are 22, 16, and 10 respectively. 1.) Find mEX 2.) Find mEY 3.) Find mXF 4.) Find mGY 11 19 11 11 5 5 Y F Z X 8 3 E G 13

8. One Final Example Find the missing measures in the following table 8π 1.) 2.) 3.) 8 6 12π 11.2 22.4 C = dp 70.2 = dp

9. Get a marker board

14. Find the circumference.

15. Find the circumference.