It is generalized by the law of cosines to triangles with any three angles.
Applicable when the spread equals one, this statement can be formulated in terms of addition using rational trigonometry. A generalization of it to inner product spaces is known as Parseval's identity, while a three-dimensional generalization is de Gua's theorem. The parallelogram law simplifies to this statement in a special case, and one proof of this theorem constructs congruent triangles whose areas are half those of a square and a rectangle. It is generalized by the law of cosines to triangles with any three angles. For 10 points, name this theorem used to find the length of the hypotenuse of a right triangle, stated as A squared plus B squared equals C squared.
Applicable when the spread equals one, this statement can be formulated in terms of addition using rational trigonometry.
{Pythagorean} theorem