1. Lesson 8.7 Circumference and Area of Circles Pages 452 - 454

2. Parts of a Circle A circle is the set of all points in a plane that are the same distance from a given point called the center. The distance from the center to a point on the circle is called a radius. The distance across the circle, that passes through the center, is called a diameter. The circumference of a circle is the distance around the circle.

3. Circumference Circumference = π diameter (C=πd) OR Circumference = π 2 radius (C=2 π r) 10 inches 4 cm

4. Area of a Circle The area of a circle is the amount of space on the inside of the figure. Area = π radius 2 (A=πr 2 ) 10 inches 4 cm

5. Area of a Sector A sector is a portion of a circle that is determined by 2 radii and a central angle. A central angle is an angle whose vertex is the center of the circle. 10 yd 70⁰

6. Find the area of the sector Area of Sector = # degrees 360⁰ π r 2 10 yd 70⁰

7. Assignment: Pages 455 – 457 #1, 3-6, 10-20, 23-26, 33-39