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finding length of a side Worksheets

Free area & perimeter worksheets with answer key. No login or account needed. From finding the area or perimeter visually to using math we've got you covered. A grading column and quick grade scale maker grading a breeze and a modified pages help with lower level learners or when just introducing a topic. Great for teachers or for homeschool.

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Finding Length of a Side

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Finding Length of a Side

About these worksheets

Students practice finding a missing side length of a rectangle or right triangle when given the area or perimeter. These worksheets reinforce the relationship between side lengths, area, and perimeter through reverse calculation — dividing area by a known side or subtracting known sides from a total perimeter. Problem sets span third grade through middle school, with some including decimal values.

finding length of a side Worksheets - Missing Side (Area) E worksheet

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Missing Side (Area) E

3md8

Use the area of a rectangle to figure out a missing side length.
Divide the area by the known side to find the unknown side.
Check that the side lengths you found make the correct area when multiplied.

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finding length of a side Worksheets - Missing Side (Perimeter) E worksheet

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Missing Side (Perimeter) E

3md8

Use the perimeter of a rectangle to figure out one missing side length.
Add the known side lengths and subtract from the total perimeter to find what is left.
Use the fact that opposite sides of a rectangle are equal to solve for the unknown side.
Write the answer with the correct measurement units.

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finding length of a side Worksheets - Finding Missing Side Length of Rectangle worksheet

Load up one problem at a time! Ideal for projectors, tablets and computers.

Create a set of flash cards.

Create a distance learning assignment.

Distance Learning

Create a new worksheet.

Create New Sheet

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Finding Missing Side Length of Rectangle

Find a missing side length of a rectangle when you know the area and one side.
Use multiplication and division to connect side lengths and area of rectangles.

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finding length of a side Worksheets - Finding Missing Side Length of Rectangle with Decimals worksheet

Load up one problem at a time! Ideal for projectors, tablets and computers.

Create a set of flash cards.

Create a distance learning assignment.

Distance Learning

Create a new worksheet.

Create New Sheet

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Finding Missing Side Length of Rectangle with Decimals

Use the area of a rectangle to figure out a missing side length.
Multiply and divide with decimals to solve for an unknown side.
Keep track of units (like square units vs. units) so the answer makes sense.
Read a rectangle diagram and match each number to the correct side.

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finding length of a side Worksheets - Finding Missing Side Length of Right Triangle (Area) worksheet

Load up one problem at a time! Ideal for projectors, tablets and computers.

Create a set of flash cards.

Create a distance learning assignment.

Distance Learning

Create a new worksheet.

Create New Sheet

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Finding Missing Side Length of Right Triangle (Area)

Use the area formula for a right triangle to find a missing side length.
Solve for the unknown base or height when the area and the other leg are given.

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