Given the two legs of a right triangle, this finds the third side and both non-right angles in one step — the “3-4-5 triangle” idea generalized to any two leg lengths.
How it works
The Pythagorean theorem (the sum of the squared legs, square-rooted) gives the hypotenuse; the arctangent of each leg’s ratio to the other gives the two non-right angles, which always add up to 90 degrees.
What this does not include
This does not include solving from one leg and one angle, or from the hypotenuse and one leg — this calculator specifically takes two legs as the known values.
How to use this calculator
- Enter the lengths of both legs (the two sides that meet at the right angle).
Frequently asked questions
Why do the two non-right angles always add to 90 degrees?
Because all three angles in any triangle sum to 180 degrees, and a right triangle already uses 90 of those on the right angle itself, leaving exactly 90 degrees split between the other two.
What’s the “3-4-5 triangle” this reminds people of?
A well-known right triangle where the legs are 3 and 4 units and the hypotenuse comes out to exactly 5 — often used by builders to check that a corner is truly square.
Does this work for any right triangle, not just 3-4-5 style ones?
Yes — the Pythagorean theorem and the angle formulas here work for any two positive leg lengths, not just whole-number “Pythagorean triple” combinations.
