Triangle

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

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References

• http://en.wikipedia.org/wiki/Triangle

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]\displaystyle{ A }[/math], B, and [math]\displaystyle{ C }[/math] is denoted [math]\displaystyle{ \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).

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