The Pythagorean Theorem

Introduction to the Pythagorean Theorem

by Socratica

Pythagorean Theorem Geometric Proof

by Socratica

Vocabulary: Parts of a Right Triangle

Right-angled triangle
Source: CK-12 Foundation

Cathetus (plural: catheti) is a side of a right-angled triangle adjacent to the right angle. Likewise, leg is a side of a right triangle that is not the hypotenuse. A side of an isosceles triangle that is not the base is also called leg. In the case of right triangles, cathetus and leg are synonyms.

Hypotenuse (alternate spelling: hypothenuse) is the side of a right-angled triangle that is opposite the right angle.