Triangle inequality ≥ b ≥ c" and "formula_8" is the golden ratio, as In the case of right triangles, the triangle inequality specializes to the statement that the hypotenuse is greater than either of the two sides, and less than their sum. The second part of this theorem is already established above for any side of any triangle. The first part is established using the lower figure. In the figure, consider the right triangle . An isosceles triangle is constructed with equal sides . From the triangle postulate, the angles in the right triangle satisfy: Likewise, in the isosceles triangle , the
Altitude (triangle) barycentric coordinates are zero for a vertex point, the barycentric coordinates given for the orthocenter show that the orthocenter is in an acute triangle's interior, on the right-angled vertex of a right triangle, and exterior to an obtuse triangle. In the complex plane, let the points and represent the numbers formula_5, formula_6 and, respectively, formula_7 and assume that the circumcenter of triangle is located at the origin of the plane. Then, the complex number is represented by the point , namely the orthocenter of triangle . From this, the following characterizations of the orthocenter by means of free vectors can