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Pythagorean Theorem Calculator

Find the missing side of a right triangle from the other two sides using a² + b² = c².

Missing side c
5
Area
6
Perimeter
12
Angle opposite a
36.8699°
Angle opposite b
53.1301°

What is Pythagorean Theorem Calculator?

The Pythagorean theorem says that in a right triangle the square of the longest side, the hypotenuse, equals the sum of the squares of the other two sides.

What this tool does

Fill in any two sides and leave the third empty. It finds the missing side and shows the area, the perimeter and the two acute angles.

How to use it

  1. Enter two of the three sides.
  2. Leave the third empty.
  3. Read the missing side, area and angles.

Did you know?

  • The triple 3, 4, 5 is the best known whole number example, and 5, 12, 13 is another.
  • The theorem is named after the Greek mathematician Pythagoras, but it was known in Babylon and India much earlier.

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