1. Circles Circumference, Diameter and Radius

2. Important Info. You’ll need: notebook, pencil, and formula card. Pause. Rewind. Volume. Questions?

3. Area & Perimeter Area: Covering Perimeter: Surrounding Polygons: Triangles, Rectangles, Squares, Parallelograms, Trapezoids

4. What is a circle? Not a polygon. A plane figure with three or more straight sides and angles. Definition: a closed plane figure made up of all the points the same distance from a point called the center.

5. E Circle E F G H EFEGEH = radius

6. E Circle E F EF diameter I + EI = IF ½ ½ radius + radius = diameter r + r = dr + r = d 2r = d2r = d

7. Things You Should Know... Radius (Plural: Radii) A straight line from the center of a circle to it circumference. It is half of the diameter. Radius = r Diameter A straight line passing through the center of a circle connecting 2 points on the circumference. It is twice the radius. Diameter = d

9. Circumference Distance around a circle. C=2πr or C=πd π = 22/7 ≈ 3.14

10. Finding Circumference C=2πr Use this formula when you are given the radius. C=πd Use this formula when you are given the diameter.

11. Find the circumference of each circle. Use 3.14 for π. 4 cm

12. Find the circumference of each circle. Use 3.14 for π. 6 in

13. Find the circumference of each circle. Use 3.14 for π. 2.1 m

14. Find the circumference of each circle. Use 3.14 for π. 3.3 ft

15. http://bit.ly/12PtlS0 How much do you know?

16. Questions Email: sgrey@spotswood.k12.nj.us llayton@spotswood.k12.nj.us maussicker@spotswood.k12.nj.us Before school tomorrow. Extra help on Mondays and Wednesdays.