2. Perimeter and Area

3. Measurement of the outside of the shape.
Perimeter of a polygon?
Measurement of the outside of the shape.

4. Perimeter of a circle?
Circumference C = 2πr

5. Area of a circle?
A = pi(radius)2 A = πr2

6. Area of a rectangle?
A = base  height A = bh

7. Area of a triangle?
A = ½ base  height A = ½bh

8. Apothem
The distance from the center to the center of a side of a regular polygon.

9. Regular pentagon DEFGH has a center C, apothem BC. GH = 13 and BC = 10
Regular pentagon DEFGH has a center C, apothem BC. GH = 13 and BC = 10. Find the perimeter and area of the polygon.

10. Area of any regular polygon?
Area = ½ (apothem)(Perimeter)
A = ½aP

11. Does this work for a square?
A = ½aP