Microsoft Word - Unit 3 - Area Measurement.doc

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3.4: Area of Regular Polygons - Notes

A regular polygon is a closed figure with all sides equal and all angles equal.

FORMULA

NAME OF SHAPE

DIAGRAM

Area = length x width

(or A = lw)

Area = x base x height

(or A = bh )

2

Area = radius 2

(orA= r 2 )

Example 1: Alison wants to carpet two rectangular bedrooms. One bedroom measures 12 ft by 15 ft. The other measures 10 by 12 ft. How much carpet does Alison need to buy?

Example 2: Trevor bought a square rug for her living room. The rug covers 250 sq ft. What are the dimensions of the rug?

Example 3: Complete the following. Divide each shape into congruent (same size and same shape) triangles.

First: Calculate the area of the square

Base = cm

Height = cm

Area of a triangle:

Area of the square:

In the regular hexagon:

Base = ___cm

Height = ___cm

Area of a triangle:

Area of the regular hexagon:

This can be done in one step

Area of the regular octagon:

Example 3: What is the area of this sandbox, rounded to one decimal place?

Example 5: A regular octagon has an area of 96 sq in. The sides of the octagon are 6 in. What is the height?