Editing Right triangle (section)

==Thales' theorem==
{{main|Thales' theorem}}
[[Image:thm mediane.svg|thumb|300px|right|Median of a right angle of a triangle]]
'''Thales' theorem''' states that if <math>BC</math> is the diameter of a circle and <math>A</math> is any other point on the circle, then <math>\triangle ABC</math> is a right triangle with a right angle at <math>A.</math> The converse states that the hypotenuse of a right triangle is the diameter of its [[circumcircle]]. As a corollary, the circumcircle has its center at the midpoint of the diameter, so the [[median (geometry)|median]] through the right-angled vertex is a radius, and the circumradius is half the length of the hypotenuse.