Solve a right triangle using the Pythagorean theorem: enter any two sides and the tool finds the third, plus the area and perimeter when you provide both legs.
How it works
- Enter two known sides of your right triangle (e.g., side a and side b).
- Leave the third unknown side blank or 0.
- The calculator uses a² + b² = c² to find the exact missing length.
Frequently asked questions
What is the hypotenuse?
The longest side of a right triangle, opposite the right angle. It must be longer than either leg.
Does this work for any triangle?
No — only right triangles. For others, use the law of cosines.
What is a 3-4-5 triangle?
A classic right triangle where 3² + 4² = 5². Any multiple (6-8-10, etc.) also works.