Area of Rectangles and Irregular Figures

Area of Irregular Polygons

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TARGET 1: Area and Volume

​Calculate the area of polygons by decomposing them into rectangles, triangles, and other shapes.

Multiple Choice

Irregular means not regular (different).

A polygon is a shape with many straight sides.

Which shape is an irregular polygon?

Finding Area of a Rectangle

We know we can find the area of a rectangle by multiplying length x width.

Multiple Choice

What is the area of this rectangle?

• 30 square centimeters

• 50 square centimeters

• 15 square centimeters

• 15 centimeters

• 30 centimeters

Multiple Choice

What does the word partition mean?

• to split or divide

• to add together

• to find the total

• the area of a rectangle

Area of an Irregular Polygon

If we partition the polygon into smaller rectangles, how would that help?

Multiple Choice

If we partition an irregular polygon into smaller rectangles...

• we can find the area of each rectangle.

• we can create a cool and colorful picture.

Area of an Irregular Polygon

There may be multiple ways to partition the polygon into rectangles!

Let's Do It!

We can walk through the steps of finding the area (or amount of space) of an irregular polygon.

Multiple Choice

How should we find the area of this irregular polygon?

• Multiply length x width

• Partition the polygon into smaller rectangles.

Partition

There are many ways we can partition this polygon into rectangles.

It is really up to you!

Multiple Choice

After we partition the polygon, what should we do next?

• Find the area of each rectangle.

  length x width

• Add up all of the numbers.

• Count the number of rectangles.

Multiple Choice

How do we find the area of the green rectangle?

• 16 x 4

• 16 x 8

• 8 x 8

• 3 x 4

• 4 x 5

Multiple Choice

How do we find the area of the red rectangle?

• 16 x 4

• 16 x 8

• 8 x 8

• 8 x 4

• 4 x 5

Multiple Choice

How do we find the area of the yellow rectangle?

• 16 x 4

• 16 x 8

• 8 x 8

• 8 x 4

• 4 x 5

Multiple Choice

What is the area of the entire irregular polygon?

(16 x 4) + (8 x 4) + (4 x 5)

• 126 square meters

• 64 square meters

• 128 square meters

• 100 square meters

• 116 square meters