freeCodeCamp/guide/english/mathematics/triangle/index.md

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title: Triangle
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## Triangle

A triangle is a polygon which has three sides and vertices, whose internal angles add up to 180 degrees.

Any side of a triangle can be considered a base (B).

The distance from the base to the vertice that does not touch it is the height (H).

### Classifications

- A right triangle is a triangle that contains one angle equal to 90 degrees.

- An acute triangle is a triangle that consists entirely of angles less than 90 degrees.

- An obtuse triangle is a triangle that contains one angle more than 90 degrees.

- An equilateral triangle's 3 sides and angles are always equal in length and degree (and therefore the angles are equal to 60 degrees).

- An isosceles triangle has 2 sides and angles that are equal in length and degree.

- A scalene triangle has no sides or angles that are equal in length or degree.

![triangle](https://upload.wikimedia.org/wikipedia/commons/e/eb/Regular_polygon_3_annotated.svg "triangle")

#### More Information:
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- [Wikipedia](https://en.wikipedia.org/wiki/Triangle)