Triangle

The triangle, or trig, is the simplest possible polygon, excluding the degenerate digon. Its highest symmetry version is called an equilateral triangle, to emphasize its three equal side lengths.

Vertex coordinates
The vertices of a triangle of edge length 1 centered at the origin are (±1/2, $\sqrt{3}$/6), (0, $\sqrt{3}$/3).

Other kinds of triangles
Beside the equilateral triangle, there are other kinds of triangles with non-equal edge lengths:

Isosceles triangle
An isosceles triangle has two of the three sides of equal length, and two of the three angles are identical.

Scalene triangle
A scalene triangle has all three sides of different length, and has three different angles.