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Mathematics vocabulary · Geometry

Pythagorean theorem

Meaning in mathematics, with examples

/pɪˌθæɡəˈriːən ˈθɪərəm/nounCore term

In mathematics, Pythagorean theorem means: The rule that in a right triangle the square of the hypotenuse equals the sum of the squares of the other two sides: a² + b² = c².

In Turkish: Pisagor teoremi, Pisagor bağıntısı

How it is used

Used to find a missing side of a right triangle and the distance between two points. You apply or use the Pythagorean theorem; in class people simply say 'use Pythagoras'. Whole-number sets such as 3, 4, 5 are called Pythagorean triples.

Example sentences

  1. By the Pythagorean theorem, the diagonal of a 6 by 8 rectangle is 10.

  2. You can only use the Pythagorean theorem if the triangle has a right angle.

Common collocations

  • apply the Pythagorean theorem
  • Pythagorean triple
  • use Pythagoras
  • by Pythagoras
  • hypotenuseThe longest side of a right triangle, which is the side opposite the right angle.
  • right angleAn angle of exactly 90 degrees, like the corner of a square, usually marked on diagrams with a small square.
  • triangleA flat shape with three straight sides and three angles; the angles inside any triangle always add up to 180 degrees.
  • theoremAn important mathematical statement that has been proved to be true, such as the Pythagorean theorem.
  • squaredMultiplied by itself; used to read a power of 2 aloud, so x² is 'x squared' and 5² = 25 is 'five squared is twenty-five'.

More terms: Geometry

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