Equilateral triangle Equilateral triangle In geometry, an equilateral triangle is a triangle in which all three sides are equal. In the familiar Euclidean geometry, an equilateral triangle is also equiangular; that is, all three internal angles are also congruent to each other and are each 60°. It is also a regular polygon, so it is also referred to as a regular triangle. Denoting the common length of the sides of the equilateral triangle as "a", we can determine using the Pythagorean theorem that: Denoting the radius of the circumscribed circle as "R", we can determine using trigonometry that: Many of these quantities
Equilateral triangle to the points where the angle bisectors of ∠"APB", ∠"BPC", and ∠"CPA" cross the sides ("A", "B", and "C" being the vertices). For any point P in the plane, with distances "p", "q", and "t" from the vertices A, B, and C respectively, For any point P on the inscribed circle of an equilateral triangle, with distances "p", "q", and "t" from the vertices, and For any point P on the minor arc BC of the circumcircle, with distances "p", "q", and "t" from A, B, and C respectively, and moreover, if point D on side BC divides PA into