Triangle vocabulary worksheet

This triangle vocabulary worksheet will really help students to test their knowledge of the different types of triangle. Students will also try to identify the names given to the sides of a right triangle. 

Name : ________________________

Date : __________________________

Using the word box below, write down the correct word next to each definition.


Right triangle
Obtuse triangle


A triangle with no congruent sides is called ___________________

For a triangle, a side opposite to a right angle is called ___________________

A triangle in which all the angles have the same measure is called___________________

A triangle with an interior angle that is equal to 90° is called ___________________

In a triangle, the line that starts from the vertex and is perpendicular to the side opposite that vertex is called ___________________

Two congruent sides of an isosceles triangle are called___________________

A triangle where each of the interior angles measures less than 90° ___________________

The noncongruent side of an isosceles triangle is called ___________________

A triangle in which all sides have the same length ___________________

A triangle with 2 congruent sides is called ___________________

A triangle with an interior angle that measures more than 90° is called ___________________

A polygon with 3 sides is called ___________________

Teachers! Do this when using the triangle vocabulary worksheet. It is like a lesson plan.

Here are some useful ideas that can help students be successful in memorizing and understanding the meaning of these words.

Have students review the lesson about the different types of triangles. They may not need everything in that lesson to answer the questions in this worksheet. Nonetheless, it will strengthen their vocabulary a lot. It may be useful to print the following table found in that lesson and give it to the students!

Naming the different types of triangles

Have students now answer the questions. Tell them that each word can only be used once.

Then, after students are done answering the questions on the worksheet, have them exchange papers so that they can get feedback from their peers.  

Here is how to check if they finally know the meaning of the twelve words above.

Take the triangle vocabulary worksheet away from them. Pick a word from the list, tell it to them, and have them explain the meaning of the word.

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