Stable Numbers
Pythagoras Calculator
Work out a missing side of a right triangle using the Pythagorean theorem. Choose which side to solve, enter the other two, and get instant results with clear working. Angles, area and perimeter are included when possible.
Right triangle with c opposite the right angle.
For labelling only. No conversion performed.
Enter the two known sides. Set the side you want to solve in “Solve for”.
Results
- a:
- b:
- c:
- Angles A, B:
- Area:
- Perimeter:
Working
Formula: c = √(a² + b²)
Substitute: c = √(² + ²)
Result: c =
Formula: a = √(c² − b²)
Substitute: a = √(² − ²)
Result: a =
Formula: b = √(c² − a²)
Substitute: b = √(² − ²)
Result: b =
c must be the longest side. All lengths are treated in the same unit.
About this calculator
This tool solves right-triangle sides using the Pythagorean theorem, a² + b² = c², where c is the hypotenuse. Pick which side to solve and enter the other two. The page shows the working, then adds extra details such as the acute angles, area and perimeter when enough information is available.
Units here are for labelling only. If you measured in centimetres, set the unit to cm and your outputs will be labelled cm. For conversions, use a converter first, then paste the converted values here. Results are calculated in your browser and the URL updates so you can share a prefilled setup.
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