Pythagorean Theorem

Formula / Rule
Pythagorean Theorem
Topic
Geometry
Formula

In a right-angled triangle:

$c^2 = a^2 + b^2$

Where $c$ is the hypotenuse (longest side).

Common Pythagorean Triples:

  • 3, 4, 5
  • 5, 12, 13
  • 8, 15, 17
  • 7, 24, 25

Related Formulas:

  • Diagonal of rectangle: $d = \sqrt{l^2 + b^2}$
  • Diagonal of square: $d = a\sqrt{2}$
When to Use
Right triangles, distance between two points, diagonal calculations.
Worked Example

Q: A right triangle has legs 6 and 8. Find hypotenuse.

$c^2 = 6^2 + 8^2 = 36 + 64 = 100$ $c = \textbf{10}$

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