The Compendium Geometry is an eBook providing facts, formulas and explanations about geometry.

Home Analytic Geometry Triangle Thales' Theorem
See also: Properties of a Right Triangle, Pythagorean Theorem 
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Thales' Theorem

The theorem of Thales can be formulated in two ways:
  • The inscribed angle in a semicircle is always a right angle.
     
  • In a right triangle, the right angle is always located on the (semi)circle whose center is at the middle of side c having a radius of c/2. This circle is always the circumcircle of the right triangle.
The semicircle over the hypothenuse of a right triangle is sometimes also called "Thales circle".

Home Analytic Geometry Triangle Thales' Theorem

Last Update: 2010-12-06