Right Triangle Calculator
Solve a right triangle given any two inputs. Enter any combination of the two legs, one leg and the hypotenuse, or a leg and an angle (degrees). The calculator returns all sides, angles, area, perimeter and the classification.
Enter any two values
Enter any two values and press Solve.
Right-triangle formulas
a² + b² = c²
A + B = 90°
Area = ½ · a · b
Perimeter = a + b + c
sin A = a / c, cos A = b / c, tan A = a / b
Special right triangles
- 45–45–90: legs equal, hypotenuse = leg × √2.
- 30–60–90: short leg = hypotenuse ÷ 2, long leg = short leg × √3.
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Frequently asked questions
Any two of: leg a, leg b, hypotenuse c, angle A, angle B. The most common pairs are two sides, a side and an angle, or the two non-right angles.
Use the inverse trigonometric functions. Given sides a and c: A = arcsin(a / c). Given a and b: A = arctan(a / b). Then B = 90° − A.
Yes — that is a 45–45–90 triangle (isosceles right triangle). Both acute angles are 45° and the hypotenuse equals each leg multiplied by √2.