Triangle their internal angles, measured here in degrees. A triangle that has two angles with the same measure also has two sides with the same length, and therefore it is an isosceles triangle. It follows that in a triangle where all angles have the same measure, all three sides have the same length, and such a triangle is therefore equilateral. Triangles are assumed to be two-dimensional plane figures, unless the context provides otherwise (see Non-planar triangles, below). In rigorous treatments, a triangle is therefore called a "2-simplex" (see also Polytope). Elementary facts about triangles were presented by Euclid in books 1–4
Triforce the American NES. The game has since made its way onto multiple consoles that still exist today. The Triforce consists of three equilateral triangles, which are joined (with an inverted empty triangle in the middle) to form a large equilateral triangle. Occasional variations are found in the shape and subdivisions. The Triforce consists of three distinct entities represented by the three smaller triangles, each of which is also referred to as a Triforce when considered individually. The triangles are referred to as the Triforce of Power, the Triforce of Wisdom, and the Triforce of Courage. In the first game, "The