Perimeter of Polygons Worksheets

Free printable worksheets with answer keys. Pick a level, preview the questions, then open the sheet to swap or delete any single question.

Grade 3CCSS 3.MD.D.8Answer key includedPDF · Print

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Easy: Triangles and quadrilaterals

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Worksheet variations

The perimeter is the distance all the way around a shape: add the lengths of all its sides. When one side is missing and the perimeter is given, add the sides you know and subtract that total from the perimeter.

EasyTriangles and quadrilaterals MediumPentagons and hexagons HardMissing side from the perimeter

How to solve it: a worked example

Find the perimeter or the missing side.

Start
Add all the sides
Answer

Common mistakes to watch for

Missing a side when adding, especially on shapes with five or six sides.
Multiplying the side lengths instead of adding them.
Adding the perimeter to the known sides instead of subtracting.

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FAQ

Is perimeter only for rectangles?

No. The perimeter of any polygon is the sum of all its sides, whether it has 3 sides or 6.

How do you find a missing side when you know the perimeter?

Add the sides you know and subtract that from the perimeter. If the perimeter is 30 cm and the other sides add to 22 cm, the missing side is 8 cm.

Is every worksheet different?

Yes. Numbers are generated each time, and the answer key is calculated for that sheet. Swap any single question and its answer updates too.

Can I mix perimeter of polygons with other skills?

Yes. In the generator, add more skills; each gets its own section on the sheet with its own instructions.

Is it free to print?

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