Right Triangle Calculator

A right triangle has one 90 degree angle. The two shorter sides that meet at that corner are the legs, and the longest side opposite the right angle is the hypotenuse.

Exactly two, and at least one must be a side length. Two legs, a leg and the hypotenuse, or one side and angle A all work. Entering only one value, or three, returns a message asking for exactly two.

A right triangle has only one free acute angle here, angle A. Angle A alone fixes the shape but not the size, so without any side length there are infinitely many triangles and no unique answer.

Angle A is the acute angle opposite Leg a, and angle B is opposite Leg b. The two acute angles always add to 90 degrees, so the tool reports angle B as 90 minus angle A.

The hypotenuse is always strictly the longest side. If you enter a leg that is equal to or longer than the hypotenuse, no real right triangle exists, so the input is rejected with an error.

Angle A is entered in degrees, so 30 means 30 degrees and must be strictly between 0 and 90. It is converted to radians internally before any sine, cosine, or tangent is applied.

Area is Leg a times Leg b divided by two, since the legs are perpendicular. Perimeter is simply the sum of Leg a, Leg b, and the hypotenuse.

Trigonometry and square roots often produce long irrational values, so every output is rounded to four decimal places for readability. Whole-number answers like the 3-4-5 triangle stay exact.

Yes. The solver runs locally in your browser and nothing is uploaded. A JSON API is also available for scripts, taking any two of legA, legB, hypotenuse, and angleADeg.