freeCodeCamp/guide/english/mathematics/special-right-triangles-intro/index.md

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title: Special Right Triangles Intro
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## Special Right Triangles Intro

Special right triangles are a type of right triangle where the two non-right angles share a special relationship.

There are two types of special right triangles: a 45-45-90, and a 30-60-90.

## 45-45-90
This type of triangle has one angle of 90<sup>o</sup>, and two angles of 45<sup>o</sup> each. This causes the triangle's sides to have this special relationship:

![45-45-90 side relationships](https://github.com/Zoonn123/resources/blob/master/45-45-90hacktoberfestedit.png)

## 30-60-90
This type of triangle has one angle of 90<sup>o</sup>, one angle of 60<sup>o</sup>, and one angle of 30<sup>o</sup>. This causes the triangle's sides to have this special relationship:

![30-60-90 side relationships](https://github.com/Zoonn123/resources/blob/master/30-60-90hacktoberfestedit.png)