Circular triangle Circular triangle In geometry, a circular triangle is a triangle with circular arc edges. A convex circular triangle may be constructed by three circles intersecting each other and represents the area of intersection. Its edges are all curved outwards. The sum of the internal angles of a circular triangle is greater than 180°. A Reuleaux triangle is a special case based on an equilateral triangle where the center of each arc is on the opposite vertex. A circular horn triangle is a similar concept, but represents the area interior to 3 mutually tangent circles so all of the internal angles
Heptagonal triangle heptagonal triangle's orthic triangle, with vertices at the feet of the altitudes, is similar to the heptagonal triangle, with similarity ratio 1:2. The heptagonal triangle is the only obtuse triangle that is similar to its orthic triangle (the equilateral triangle being the only acute one). The various trigonometric identities associated with the heptagonal triangle include these:, The cubic equation has solutions formula_66 and formula_67 which are the squared sines of the angles of the triangle. The positive solution of the cubic equation equals formula_69 which is twice the cosine of one of the triangle’s angles. We also have: For an