About the pythagorean theorem calculator
In a right triangle, the square of the hypotenuse equals the sum of the squares of the other two sides. This calculator solves for whichever side you’re missing and also shows the triangle’s area. It’s useful for homework, rafters, ramps, and checking that corners are square.
How to use this calculator
- Choose whether you’re solving for the hypotenuse or a leg.
- Enter the two known sides in the same unit.
- Read the missing side.
Worked examples
- a = 3, b = 4
- c = √(9 + 16) = √25 = 5
Hypotenuse = 5.
Measurement guidance
Squaring a corner
Measure 3 ft along one side and 4 ft along the other; if the diagonal is exactly 5 ft, the corner is square. Multiples such as 6-8-10 work for larger layouts.
Frequently asked questions
Does this work for any triangle?
Only right triangles (with a 90° angle).
Which units should I use?
Any, as long as both sides use the same unit.
Why must c be longer than the leg?
The hypotenuse is always the longest side of a right triangle.