Geometry

Pythagorean Theorem Calculator

Find a missing side of a right triangle using a^2 + b^2 = c^2, with substitution steps.

Find a missing right-triangle side

a = 3b = 4c = 5ABC
Answer
c = 5

How to use the pythagorean calculator

Use this calculator when a right triangle has two known sides and one missing side.

  1. Choose which side is missing.
  2. Enter the two known side lengths.
  3. Substitute into the Pythagorean theorem.
  4. Take the square root to find the missing side.

Formula or method

a^2 + b^2 = c^2, where c is the hypotenuse.

Worked examples

Find hypotenuse

Problem: a = 3, b = 4

Solution: c = sqrt(3^2 + 4^2) = sqrt(25) = 5.

Find a leg

Problem: c = 13, a = 5

Solution: b = sqrt(13^2 - 5^2) = sqrt(144) = 12.