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Pythagorean Theorem Calculator
Solve the missing side of a right triangle using the Pythagorean theorem.
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Right-triangle utility
Interactive calculator
Solve right triangles with the Pythagorean theorem
Choose which side is missing, enter the known sides, and calculate the remaining side of a right triangle.
Results
Leg A
3
Leg B
4
Hypotenuse
5
How to use it
- 01Choose which side you want to solve for.
- 02Enter the known side lengths.
- 03Review the completed right triangle with the missing side filled in.
Result guide
- The hypotenuse must always be the longest side in a valid right triangle.
- When solving for a leg, the hypotenuse must be larger than the known leg.
- This calculator is limited to right triangles, not arbitrary triangles.
Why this page matters
The Pythagorean theorem is one of the most-used geometry relations because right triangles show up in math, construction, surveying, and engineering.
A useful page should solve either the hypotenuse or a missing leg so the user does not need separate tools for different right-triangle setups.
Frequently asked questions
Why must the hypotenuse be the longest side?
Because it lies opposite the right angle and is always longer than either leg in a right triangle.
Can this solve any triangle?
No. The Pythagorean theorem applies specifically to right triangles.
How is this related to the distance formula?
The distance formula is essentially the Pythagorean theorem applied to coordinate differences.
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