Right triangle and "G" and hypotenuse "A", then and where formula_40 is the golden ratio formula_41 Since the sides of this right triangle are in geometric progression, this is the Kepler triangle. Thales' theorem states that if "A" is any point of the circle with diameter "BC" (except "B" or "C" themselves) "ABC" is a right triangle where "A" is the right angle. The converse states that if a right triangle is inscribed in a circle then the hypotenuse will be a diameter of the circle. A corollary is that the length of the hypotenuse is twice the distance from the right
Medial triangle of "ABC": the parallel to "AB" through "C", the parallel to "AC" through "B", and the parallel to "BC" through "A". Trilinear coordinates for the vertices of the anticomplementary triangle, X'Y'Z', are given by The name "anticomplementary triangle" corresponds to the fact that its vertices are the anticomplements of the vertices A, B, C of the reference triangle. The vertices of the medial triangle are the complements of A, B, C. Medial triangle Each side of the medial triangle is called a "midsegment" (or "midline"). In general, a midsegment of a triangle is a line segment which joins the midpoints