IXL | Pythagorean theorem: find the perimeter

What is the perimeter? If necessary, round to the nearest tenth.

feet

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Learn with an example

question

What is the perimeter? If necessary, round to the nearest tenth.

inches

key idea

In a right triangle,

where

and

are the lengths of the legs and

is the length of the hypotenuse. This is called the Pythagorean theorem.

solution

Use the Pythagorean theorem, with

and

Pythagorean theorem

Plug in

and

Plug in

and

Square

225

Square

Subtract 81 from both sides

144

Subtract 81 from both sides

Take the square root of both sides

144

Take the square root of both sides

Simplify

The length of the missing leg is 12 inches.

Find the perimeter. Add the lengths of the two sides and the hypotenuse.

The perimeter is 36 inches.

Looking for more? Try these:

Lesson: The Pythagorean theorem

Lesson: Perimeter

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Teacher tools

Work it out

Not feeling ready yet? These can help:

T.3Pythagorean theorem: find the missing leg or hypotenuse length

V.1Perimeter

Lesson: The Pythagorean theorem

Lesson: Perimeter

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