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5 Free Find Missing Side When Given Perimeter Worksheet | Fun Activities

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These find missing side when given perimeter worksheet will help to visualize and understand perimeter and number systems. 3rd to 5th-grade students will learn basic methods for finding missing sides in a geometrical shape and can improve their basic math skills with our free printable finding missing sides worksheets.


5 Fun Find Missing Side When Given Perimeter Worksheet

Please download the following missing side worksheets and find all the missing sides on the pages.


Find Missing Side When Given Perimeter Worksheet Box Image

Triangle Missing Side

Worksheet #1

Quadrilateral Missing Side

Worksheet #2

Polygon Missing Side

Worksheet #3

Irregular Shape Missing Side

Worksheet #4

Word Problems

Worksheet #5


Introduction to Perimeter

Before going to the main discussion, we will discuss a thing or two about the perimeter. First, we will know what the perimeter is.

In geometry, we have been introduced to various types of shapes. Perimeter is the total length that covers the outside of a shape. Let us explain it to you with an example.

See the following image. Where you will see a rectangle whose opposite sides are equal in length. To find the perimeter of this rectangle shape, we have to add all the sides. After that, we get the desired perimeter for this rectangle, which is 14 units.

Explaining Perimeter


Find Missing Sides of Triangles Worksheet

A triangle is the most basic form of a polygon, with only three sides. So, we thought to find the missing side of a triangle using the given perimeter as our first activity.

See the following image to understand the whole process, then proceed to solve the worksheets one by one.

Finding Missing Side of Triangle

By understanding the above image, try to solve the following missing side of triangle problems when the perimeter is given.


Find Missing Sides of Quadrilaterals Worksheet

In the first worksheet, you have to find the missing sides of some quadrilaterals. As we know, quadrilaterals have four sides, so finding the missing perimeter for quadrilaterals can be fun.

As we know, squares, rectangles, parallelograms, rhombuses, etc. are some of the known quadrilaterals. You have to have an idea about each of them to find the missing side.

Finding Missing Side of Rectangle

By understanding the above image, try to solve the following missing side of quadrilateral problems when the perimeter is given.


Find Missing Sides of Polygons Worksheet

In this section, you will find the missing side of polygons that have more than four sides. What you have to do is-

  • Add the lengths of all the given sides.
  • Find the perimeter and subtract the length of all sides from the perimeter.
  • The result is the length of the missing side.

Finding Missing Side of Octagon

By understanding the above image, try to solve the following missing side of polygon problems when the perimeter is given.


Find Missing Sides of Irregular Shapes Worksheet

We found missing sides for regular shapes in our previous discussion. In this worksheet, you are going to find the missing sides of some irregular shapes. Follow the simple steps to find the side.

  • Add the lengths of all given sides.
  • Find the perimeter and subtract the length of all sides from the perimeter.
  • The result is the length of the missing side.

Find Missing Side When Given Perimeter Word Problems Worksheet

Finally, solve some word problems related to finding missing sides. Here, the problems will not be present directly like the previous examples. Rather you have to read the word problem carefully to make the correct equation for finding the missing sides.


Download Free Printable Worksheet

Download the following combined PDF and enjoy your practice session.


So today, we’ve discussed find missing side when given perimeter worksheet using the concepts of the perimeter of various regular and irregular polygons with some interactive visual and word problems. Download our free worksheets, and after practicing these worksheets, students will surely improve their mathematical skills and have a better understanding of the relationship between perimeter and missing side.

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