What Is a Right Triangle Calculator?
This calculator solves a complete right triangle — hypotenuse, area, perimeter, and both non-right angles — from just the two leg lengths, using the Pythagorean Theorem and basic trigonometry.
How to Use the Right Triangle Calculator
- Enter the lengths of the two legs (the sides forming the right angle).
- View the hypotenuse, area, perimeter, and both angles instantly.
Right Triangle Formulas
Worked Example
Hypotenuse: √(6² + 8²) = √100 = 10
Area: ½ × 6 × 8 = 24
Perimeter: 6 + 8 + 10 = 24
Angle A: arctan(6/8) ≈ 36.87°, Angle B ≈ 53.13°
Understanding Your Results
In a right triangle, the two legs meet at the 90° angle, and the hypotenuse is always the longest side, opposite that right angle. The two non-right angles always sum to 90° (since all three angles must total 180°).
Common Mistakes to Avoid
- Confusing which leg is "opposite" which angle when using trigonometric ratios.
- Forgetting that this calculator assumes a true 90° angle between the two entered legs.
- Using degrees vs. radians inconsistently in manual trigonometric calculations.
Frequently Asked Questions
Use the Pythagorean Theorem: c = √(a² + b²), where a and b are the two legs.
Use the arctangent function: Angle A = arctan(a/b), and since all angles sum to 180°, Angle B = 90° − Angle A.
Multiply the two legs together and divide by 2: Area = ½ × a × b, since the legs serve as the base and height.
Yes — since all three angles of any triangle sum to 180°, and one angle is 90°, the remaining two must sum to 90°.
This calculator solves the entire triangle (area, perimeter, and angles) from two legs, while the Pythagorean Theorem calculator focuses specifically on finding a single missing side.