1. HONORS GEOMETRY 10.1. Circles and Circumference

2. Circle Set of all points in a plane equidistant from a given point (called the center of the circle)

3. Parts of Circles- Radius:

4. Parts of Circles- Chord

5. Parts of Circles- Diameter

6. Example One: Identify each of the lines in the picture below as either a radius, chord, or diameter.

7. You Try! Identify each of the lines in the picture below as either a radius, chord, or diameter.

8. Radius to Diameter Relationship

9. Example Two: The diameter of Circle F is 5 units and the diameter of circle G is 6 units. Find BF and AB.

10. Example Three: The diameters of circle L and circle M are 20 and 13 units respectively and QR = 4. Find LQ and RM.

11. You Try! The diameters of Circle A, B and C are 8 inches, 18 inches and 11 inches respectively. Find the measure of FG and FB.

12. Circumference

13. Example Four: In 2005, Roger Federer and Andre Agassi played tennis on the helipad of the Burji Al Arab hotel in the United Arab Emirates. The helipad has a diameter of 79 feet and is nearly 700 feet high. Find the circumference of the helipad

14. You Try! Find the circumference of each described circle - Radius is 2.5 cm - Diameter is 16 feet

15. Example Five: Find the diameter and radius of a circle to the nearest hundredth if the circumference of the circle is 106.4 mm.

16. You Try! Find the diameter and radius of a circle to the nearest hundredth if the circumference of the circle is 77.8 cm.

17. Example Six: A square with side length of 9 inches is inscribed in Circle J. Find the exact circumference of Circle J.

18. Example Seven: Find the exact circumference of circle D.

19. Example Eight: Find the exact circumference of the circle below

20. You Try! Determine the exact circumference of each of the given circles below

21. Practice Problems Try some on your own/in your table groups. As always if you are confused don’t hesitate to ask me questions OR talk to your table group– they are your greatest resource!

22. Exit Ticket: Find the exact circumference of the given circle to the left and then name one chord, radius and diameter in the circle on the right.