Right Triangle Calculator
Calculate the hypotenuse, area, perimeter, and both acute angles of a right triangle from its two legs.
- Free to use
- Accurate results
- No registration required
- Works on all devices
Enter the two legs of a right triangle to calculate its hypotenuse, area, perimeter, and both acute angles.
Your result
5
Hypotenuse (c)
Area6
Perimeter12
Angle opposite leg a36.87
Angle opposite leg b53.13
AI explanation
Formula
c = √(a² + b²); area = ab/2; angle A = arctan(a/b); angle B = 90° − angle AWorked example
Classic 3-4-5 right triangle
| Field | Value |
|---|---|
| First leg (a) | 3 |
| Second leg (b) | 4 |
| Hypotenuse (c) | 5 |
| Area | 6 |
| Perimeter | 12 |
| Angle opposite leg a | 36.8699 |
| Angle opposite leg b | 53.1301 |
Assumptions
- The two legs meet at a 90° angle by definition of a right triangle.
- The two acute angles always sum to exactly 90°.
Frequently asked questions
How is the area of a right triangle calculated?
Area = (leg a × leg b) / 2, since the two legs serve as the base and height of the triangle.
How are the acute angles calculated?
Angle A (opposite leg a) = arctan(a / b). Since all three angles in a triangle sum to 180° and one angle is 90° by definition, angle B is simply 90° − angle A.
What if I just need the hypotenuse?
Use the Pythagorean Theorem Calculator for a simpler, hypotenuse-only version of this calculation.