SB En Geom 10­3 Completed.notebook
Lesson 10­3
November 20, 2012
Areas of Regular Polygons
center or a regular polygon ­ center of the circumscribed circle
radius ­ the distance from the center to a vertex
apothem ­ the perpendicular distance from the center to a side
Center
Radius
Apothem
Nov 17­5:21 PM
Expl 1. Find the angle measures of a regular pentagon.
3 2
1
Ckpt 1. Find the angle measures in a regular octagon. 2
1
3
Nov 17­5:26 PM
1
SB En Geom 10­3 Completed.notebook
Thm 10­6
November 20, 2012
Area of a Regular Polygon
A = ½ap
a = apothem, p = perimeter
Expl 2. Find the area of a regular dodecagon with a 12.3 in. apothem and 8 in. sides.
Ckpt 2. Find the area of a regular pentagon with 11.6 cm sides and an 8 cm apothem. Nov 17­5:31 PM
Expl 3. Find the area of the regular hexagon used in the boat.
Round to the nearest mm.
600
300
a
10 mm
5 mm
Ckpt 3. The side of a regular hexagon is 16 ft. Find the area of the hexagon.
Nov 17­6:48 PM
2
SB En Geom 10­3 Completed.notebook
November 20, 2012
Extra. Find the area of the regular triangle to the nearest square inch.
12.7in
Nov 17­6:52 PM
Homework
Lesson 10­3
1­22, 39­41
Nov 17­6:58 PM
3