Solve any triangle from three known values using the sine and cosine rules.
For a right triangle, the Pythagorean theorem gives the hypotenuse c = √(a² + b²). The area is half the product of the two legs, and the two non-right angles are found with the arctangent of the leg ratio.
Hypotenuse — Pythagorean theorem
c = √(a² + b²)
Angles — Law of Sines (right triangle)
a / sin(A) = b / sin(B) = c / sin(90°) = c → A = arctan(a / b), B = 90° − A
Area
Area = (a × b) ÷ 2
Perimeter
Perimeter = a + b + c
This calculator assumes a right triangle (one 90° angle) defined by its two perpendicular legs. Other triangles need side-angle-side or law-of-cosines methods.
It's unit-agnostic — enter both legs in the same unit and all outputs use that unit (area is in that unit squared).