Free OnlineCalculators & Converters
Right Triangle Calculator
Solve any right triangle given 2 known values: sides a, b, c (hypotenuse) or acute angles A and B. Calculates all sides, angles, area, and perimeter.
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Enter any 2 known values (sides a, b, c or angles A, B). Side c is the hypotenuse. Angles A and B are opposite to sides a and b respectively.
Key Features — Right Triangle Calculator
Solve with any 2 known values
Calculates all 3 sides and 2 angles
Area and perimeter
Pythagorean theorem verification
Works with sides only, angle + side, or two angles
Why Use This Tool — Right Triangle Calculator
Free Online Right triangle calculatorSolve right triangle — for EveryoneFast & Easy Right triangle sides calculatorHypotenuse calculator — 100% FreeFree Online Right angle triangle calculator
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Frequently Asked Questions — Right Triangle Calculator
How do I solve a right triangle?
A right triangle has one 90° angle (C), two acute angles (A and B where A+B=90°), and three sides: a (opposite A), b (opposite B), and c (hypotenuse, the longest side). Given any 2 known values, all others can be found using: the Pythagorean theorem (a²+b²=c²), sine (sin A = a/c), cosine (cos A = b/c), and tangent (tan A = a/b).
What are the standard right triangle ratios?
Common right triangle ratios: 3-4-5 (angles ≈ 36.87°, 53.13°), 5-12-13, 8-15-17. Special triangles: 45-45-90 (sides ratio 1:1:√2) and 30-60-90 (sides ratio 1:√3:2). These ratios allow exact computation without a calculator.
How is area calculated for a right triangle?
Area = (1/2) × base × height = (1/2) × a × b, where a and b are the two legs (not the hypotenuse). For a right triangle with legs 3 and 4, area = (1/2)(3)(4) = 6 square units.