Types of Triangles

Types of Triangles

by Clarine Stewart

Classifying Triangles by their Sides​

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​Triangles have special names based on the length of the sides and their angles

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​When you classify triangles by their side lengths, you use the words

 equilateral, isosceles, and scalene.

​Equilateral Triangle

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An equilateral triangle has 

three equal sides.

• This is an example of a equilateral triangle.

Multiple Choice

Which of these is an equilateral triangle?

​Isosceles Triangle

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• An isosceles triangle has 

two equal sides.

• This is an example of an isosceles triangle.

Multiple Choice

Which of these is an isosceles triangle?

Scalene Triangle

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• A scalene triangle has 

no equal sides.

• This is an example of scalene triangle.

Multiple Choice

Which of these is a scalene triangle?

Classifying Triangles by angles

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​Classifying triangles by angle measure

​​When you classify triangles by their angle measures, you pay attention to whether their angles are

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• ​less than a right angle

• ​more than a right angle

• ​or a right angle

​Equilateral Triangle

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An equilateral triangle has three equal angles less than a right angle.

Multiple Choice

Which of these is an equilateral triangle?

​Right-Angled Triangle

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A right-angled triangle has one right angle.

• Right angles are represented by a rectangle.

Multiple Choice

Which of these is a right-angled triangle?

​Isosceles Triangle

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An isoceles triangle can have 

• two equal angles

• it can be more than a right angle.

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Multiple Choice

Which of these is an isosceles triangle?

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​Classifying triangles two ways

• This is a right-angled isosceles triangle.

• It has a right angle and two equal sides.