c = 15
Right Triangle Calculator
Use this free right triangle calculator to enter two sides and find the missing side, area, perimeter, hypotenuse, and acute angles.
Formula steps Examples included Copy results Private history
Hypotenuse15 cm
- Area
- 54 cm^2
- Perimeter
- 36 cm
- Acute angles
- 36.8698976458 degrees, 53.1301023542 degrees
Steps
- Use the Pythagorean theorem to complete the side lengths.
- Use area = leg a x leg b / 2.
- Use sine ratios to find the two acute angles.
- The main result is 15 cm.
How to use the right triangle calculator
- Choose two legs or leg and hypotenuse mode.
- Enter the known side lengths and optional unit label.
- Press Calculate right triangle to find sides, area, perimeter, and acute angles.
- Use examples, recent answers, or copy the result while solving right triangles.
Common uses
Complete a right triangle from two known side lengths.
Find hypotenuse, missing leg, area, perimeter, and angles together.
Check 3-4-5, 5-12-13, and other right-triangle examples.
Copy right-triangle formula steps into notes or homework.
Examples
missing leg = 12
Area = 6
Frequently asked questions
Quick answers about formulas, units, valid measurements, examples, copying, and private in-browser history.
What does the Right Triangle Calculator find?
It finds the missing side, hypotenuse, area, perimeter, and the two acute angles for a right triangle.
What inputs can I use?
Use two legs mode when both legs are known. Use leg and hypotenuse mode when you know one leg and the hypotenuse.
How are the angles calculated?
After the sides are known, the calculator uses sine ratios to estimate the two acute angles. The third angle is always 90 degrees.
What formula is used for area?
Right triangle area uses A = leg a x leg b / 2.
How is this different from the Pythagorean Theorem Calculator?
The Pythagorean tool focuses on one missing side. This calculator also shows area, perimeter, and angles.
Is my right triangle history private?
Yes. Recent right triangle answers stay only in the current browser tab while you use the page. They are not sent to a server.