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?

Fill in the Blank

What type of triangle is this?

Fill in the Blank

What type of triangle is this?

Fill in the Blank

What type of triangle is this?

Fill in the Blank

What type of triangle is this?

Fill in the Blank

What type of triangle is this?

​Classifying triangles two ways

• This is a right-angled isosceles triangle.

• It has a right angle and two equal sides.