Pythagorean theorem

American  

noun

Geometry.

1. the theorem that the square of the hypotenuse of a right triangle is equal to the sum of the squares of the other two sides.

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Pythagorean theorem Scientific  

/ pĭ-thăg′ə-rē′ən /

1. A theorem stating that the square of the length of the hypotenuse of a right triangle is equal to the sum of the squares of the lengths of the other sides. It is mathematically stated as c ² = a ² + b ², where c is the length of the hypotenuse and a and b the lengths of the other two sides.

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Etymology

Origin of Pythagorean theorem

First recorded in 1905–10

Example Sentences

We still use the Pythagorean theorem and euclidean principles.

From Slate • Sep. 26, 2025

The Pythagorean theorem is therefore equivalent to the equation sin2 x + cos2 x = 1.

From Scientific American • Apr. 10, 2023

Socrates's takeaway is that the boy had innate knowledge of the Pythagorean theorem all along; the questioning just helped him express it.

From Scientific American • Mar. 7, 2023

Fortunately, there’s a much easier way to use the Pythagorean theorem on a job site.

From Seattle Times • Dec. 12, 2022

He or his disciples discovered the Pythagorean theorem: the sum of the squares of the shorter sides of a right triangle equals the square of the longer side.

From "Cosmos" by Carl Sagan