Find the Missing Side Lengths of the Polygon

Given the perimeter, find the missing side-length.

What is the perimeter of this polygon? (Find the length of the missing sides first)

The perimeter of an isosceles triangle is 23 cm. What is the measure of side x?

Leila wants to build a mini house for her pet raccoon in the shape of a parallelogram. The perimeter must be exactly 340 cm and the short side with the door must be 73 cm. What must be the length of the longest side in centimetres?

Find the length of the missing side of the shape. The perimeter is 66 centimeters. Make sure to include the units in your answer!

Jonathan has an octagon dog pen at home that is 16 feet long when stretched out from end to end. When he shapes it back into an octagon, what is the length of one side?

• 2 feet

• 4 feet

• 2.7 feet

• 2.3 feet

Look at the composite figure. How could you find the perimeter of the figure?

• Add the four side lengths shown in the diagram.

• Divide the figure into two rectangles. Find the perimeter of each rectangle. Add the two perimeters.

• Find the two missing side lengths and add them to the four side lengths shown in the diagram.

• Multiply the four side lengths shown in the diagram.

What are the two missing side lengths?

• 6 cm and 2 cm

• 4 cm and 7 cm

• 9 cm and 7 cm

• 6 cm and 10 cm

Find the unknown side length if the perimeter is 30 cm.

• 5 cm

• 4 cm

• 8 cm

• 10 cm

Find the unknown side length if the perimeter is 29 cm.

• 10 cm

• 8 cm

• 6 cm

• 7 cm