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What Is the Sum of Angles of a Triangle?

You know that a triangle is a geometric figure with three sides (edges) and three corners (angles). That’s how it got its name! If you use a protractor and measure all the angles in a triangle, you will find that the sum of the angles is always equal to 180°.

Rule

Sum of Angles of a Triangle

The sum of all three angles in a triangle is always 180°.

There are four types of triangles: equilateral triangles, isosceles triangles, right triangles and all other triangles that can’t be categorized in any of the previous three ways— we call these types of triangles scalene triangles. These types of triangles have three different angles and therefore, also three different side lengths.

Equilateral, isosceles, right and scalene triangle

Equilateral, isosceles, right and scalene triangle

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What Is a Triangle?
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