Free Right Triangle Calculator Online
This free online right triangle calculator finds all sides, angles, area, and perimeter from any two known values. Includes an interactive triangle diagram.
Right Triangle (enter any 2)
Fill in exactly two fields. Leave the rest empty.
Right Triangle Results
Enter two values above
How the Right Triangle Calculator Works
The right triangle calculator solves any right triangle given two known values. Enter two sides, one side and one angle, or any valid combination. The right triangle calculator uses the Pythagorean theorem (a² + b² = c²) and trigonometric functions (sin, cos, tan) to find all unknowns.
For example, with side a = 3 and side b = 4: hypotenuse c = √(9+16) = 5. Angle A = arctan(3/4) ≈ 36.87°. Angle B = 90° − 36.87° = 53.13°. Area = 0.5 × 3 × 4 = 6. The right triangle calculator shows all these results with a visual diagram.
The right triangle calculator handles all input combinations: two sides, one side and one acute angle, or hypotenuse and one side. It validates inputs and shows clear error messages if the values do not form a valid right triangle.
Right Triangle Formulas
Pythagorean Theorem
c = √(a² + b²)
Area
A = ½ × a × b
Perimeter
P = a + b + c
Angle from Sides
A = arctan(a / b)
Tips for Using the Right Triangle Calculator
Enter Exactly Two Values
The right triangle calculator needs exactly two known values to solve. Fill in two fields and leave the rest empty.
Angles in Degrees
Enter angles in degrees (not radians). Each acute angle must be between 0° and 90°. The right triangle calculator converts internally.
Check the Diagram
The right triangle calculator draws a proportional SVG triangle. Use it to visually verify your inputs match the expected shape.
Common Triples
Common right triangles: 3-4-5, 5-12-13, 8-15-17, 7-24-25. Try them in the right triangle calculator to verify.
Frequently Asked Questions
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