A closed two-dimensional polygon bounded by three straight-line segments. The sum of its interior angles is always 180?. The formula with which to find an equilateral triangle's area is 0.433 times the length of one side squared. The formula for finding any triangle's area: half of the longest side multiplied by its height.Quote: "On a square lattice at least one coordinate of an equilateral triangle must be irrational. An irrational number has no finite numerical representation. An equilateral triangle represented on a computer is inherently imprecise." Ken Goldberg (born Nigeria, 1961-), American artist.Related resources: An isometric grid: a grid or blank graph of equilateral triangles. Also see mathematics, positive, regular, shape, spandrel, and vertex.