Right Triangle Calculator
Solve a right triangle with a² + b² = c² — enter any two of the legs a and b and the hypotenuse c, and leave the side you want solved blank.
Formula: a² + b² = c²
Sides, angles, area, and perimeter of any right triangle
Enter any two of the legs a and b and the hypotenuse c and the panel applies the Pythagorean theorem a² + b² = c², updating live as you type. Two legs give the hypotenuse c = √(a² + b²); a leg and the hypotenuse give the other leg √(c² − leg²). It also reports the two acute angles in degrees (α opposite leg a and β = 90 − α opposite leg b), the area ½·a·b, and the perimeter a + b + c, with a copy button for a one-line summary.
Each side must be a positive number, and you must fill in exactly two so there is a third to solve for; when a leg and the hypotenuse are given, the hypotenuse must be longer than the leg or the triangle is impossible. A neutral empty state and inline messages naming the offending field keep it from ever rendering NaN or Infinity. Everything is computed in your browser with no network calls. Oblique (non-right) triangles, the law of sines and cosines, SSS/SAS/ASA solving, and graph plotting are out of scope.