# Triangle

A triangle is a three-sided (and three-angled) polygon.

Triangle is an elementary-school-level concept. It is listed in the California State Standards for kindergarten.

### Examples

Equilateral Triangle: | A triangle in which all three sides are of equal length. In such a triangle, the angles are all equal as well. |

Isosceles Triangle: | An isosceles triangle is a triangle having (at least) two sides of equal length, and therefore also with (at least) two equal angles. |

Right Triangle: | A right triangle is a triangle that has a right angle. The Pythagorean Theorem is a relationship among the sides of a right triangle. |

### Prerequisites

Polygon: | A polygon is a two-dimensional figure that consists of a collection of line segments, joined at their ends. |