IXL | Relationship between area and perimeter: find the perimeter

The rectangles below have the same area.

4 km

6 km

3 km

What is the perimeter of the red rectangle?

kilometers

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Learn with an example

question

The rectangles below have the same area.

3 mi

6 mi

2 mi

What is the perimeter of the brown rectangle?

miles

key idea

Rectangles with the same area can have different perimeters.

solution

Find the area of the red rectangle.

3 × 6 = 18

Both rectangles have an area of 18 square miles. Find the missing side length of the brown rectangle.

You know that one of the sides is 2 miles long. Divide the area by 2 to find the missing side length.

18 ÷ 2 = 9

The brown rectangle is 9 miles by 2 miles. Find its perimeter.

9 + 2 + 9 + 2 = 22

The perimeter of the brown rectangle is 22 miles.

Looking for more? Try these:

Lesson: Rectangles

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Teacher tools

Work it out

Not feeling ready yet? These can help:

OO.10Find the area of rectangles and squares

HH.3Find the perimeter of rectangles using formulas

Lesson: Rectangles

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