IXL | Perimeter: find the missing side length

The perimeter of the shape is

units

What is the length of the missing side?

units

ref_doc_title.

Learn with an example

question

The perimeter of the triangle is

units

What is the length of the missing side?

units

key idea

The perimeter of a shape is the distance around the shape. It is the total length of the shape's sides.

solution

The perimeter of the triangle is

units

The length of one side is missing.

units

To find the missing side length, write an addition sentence for the perimeter of the triangle. The perimeter of a triangle equals the sum of all of its side lengths.

perimeter

The perimeter is

units

Add the lengths of the sides you know.

Find the side length that makes the addition sentence true.

The missing side length is

units

Looking for more? Try these:

Lesson: Perimeter

$Confetti$

Excellent!

Now entering the Challenge Zone—are you ready?

Questions
answeredQuestions

Time
elapsedTime

hr	min	sec
00	00	06

SmartScore
out of 100
IXL's SmartScore is a dynamic measure of progress towards mastery, rather than a percentage grade. It tracks your skill level as you tackle progressively more difficult questions. Consistently answer questions correctly to reach excellence (90), or conquer the Challenge Zone to achieve mastery (100)! Learn more

Teacher tools

Work it out

Not feeling ready yet? These can help:

PP.5Perimeter of polygons

P.6Subtract two-digit numbers - with regrouping

P.5Subtract two-digit numbers - without regrouping

N.15Add three numbers up to two digits each

Lesson: Perimeter

Excellent! You got that right!

Jumping to level 1 of 1

Excellent!