Solve Any Right Triangle With the Pythagorean Theorem
The Pythagorean theorem states that in a right triangle the square of the hypotenuse equals the sum of the squares of the other two sides, written a² + b² = c². This free calculator puts that idea to work: give it any two sides and it returns the third, along with the two non-right angles, the area and the perimeter.
It handles every common case. If you know the two legs, it finds the hypotenuse. If you know the hypotenuse and one leg, it finds the missing leg. Leave one field blank and the tool fills it in, then uses trigonometry to work out the angles in degrees.
The result updates instantly, so it is perfect for homework, woodworking, construction layout and any quick geometry check. There is nothing to download and nothing is sent to a server.
How to use it
- Enter any two of the three sides (a, b or hypotenuse c).
- Leave the third side blank.
- Tap solve to see the missing side, angles, area and perimeter.
Frequently asked questions
What is the Pythagorean theorem?
In a right triangle, the square of the hypotenuse equals the sum of the squares of the other two sides: a² + b² = c².
How do I find the hypotenuse?
Enter the two legs and leave the hypotenuse empty. The tool computes c = sqrt(a² + b²).
What if I know the hypotenuse and one leg?
Enter the hypotenuse and one leg, leaving the other leg empty. The tool computes the missing leg with b = sqrt(c² - a²).
Can this calculator find the angles too?
Yes. Once the three sides are known it uses trigonometry to return the two non-right angles in degrees, plus area and perimeter.
Results assume the input describes a valid right triangle. Please double-check critical measurements.