# Triangle

(Redirected from triangle)

**See:** Polygon, Three, Side, Triangle Inequality Theorem, Square.

## References

A **triangle** is one of the basic shapes of geometry: a polygon with three corners or vertices and **three** sides or edges which are line segments. A triangle with vertices [math]A[/math], *B*, and [math]C[/math] is denoted [math]\triangle[/math] *ABC*.

In Euclidean geometry any three non-collinear points determine a unique triangle and a unique plane (i.e. a two-dimensional Euclidean space).