9.2 Find the Area of Combined Rectangles

9.2 Find the Area of Combined Rectangles

I can find the area of a figure made of combined rectangles.

Step it Out Problem One

Brody and his dad are designing a tree house. The diagram shows the shape of the floor. What is the total area of the floor?

Multiple Choice

Which equation would I use to find the area of rectangle A?

• 6 x 8 = A

• 6 x 15 = A

• 8 x 16 = A

• 16 x 15 = A

We would use 6 x 8 = A

The length of Rectangle A is 8 feet, and the width is 6 feet.

A = 8 × 6, so the area of Rectangle A is 48 square feet.

Multiple Choice

Which equation would I use to find the area of rectangle

B?

• 6 x 8 = A

• 6 x 15 = A

• 8 x 16 = A

• 16 x 15 = A

We would use 16 x 15 = A

The length of Rectangle B is 16 feet, and the width is 15 feet.

A = 16 × 15, so the area of Rectangle B is 240 square feet.

Multiple Choice

48 square feet + 240 square feet =

• 280

• 288

• 298

The total area of rectangles A and B is 288

The area of Rectangle A is 48 square feet. The area of Rectangle B is 240 square feet. 48 + 240 = 288, so the total area is 288 square feet.

Step it Out Problem 2

Brody cut an opening for a window in the wall of the tree house. What is the area of the wall? 

Fill in the Blanks

What is the total length of the entire rectangle?

The total length is 8. This means the area of the rectangle is 48.

To find the measure of the longest side, you add 6 ft and 2 ft. The length is 8 ft, and the width is 6 ft. Substitute the length and width measures in the formula for the area of the rectangle. A = 8 × 6, so the area of the whole wall is 48 square feet.

Fill in the Blanks

What is the area of the cut-out space?

The area is 6 square feet.

The length of the window is 3 ft, and the width is 2 ft.

A = 3 × 2, so the area of the window is 6 square feet.

Multiple Choice

48 square feet – 6 square feet =

• 54

• 42

• 41

The area of the wall is 42 square feet.

To find the area of the wall, subtract the area of the window from the area of the whole wall. 48 – 6 = 42, so the area of the wall is 42 square feet.