Right Triangle Calculator
Calculate the missing side, hypotenuse, area, and angles of a right triangle using the Pythagorean theorem and basic trigonometry.
Calculate a right triangle
Enter any two known side lengths or select the calculation you need. The calculator will determine the missing measurements and show the calculation step by step.
Your result
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| Calculation | — |
| Input 1 | — |
| Input 2 | — |
| Hypotenuse | — |
| Area | — |
| Angles | — |
Step-by-step calculation
What is a right triangle?
A right triangle is a triangle with one angle measuring exactly 90 degrees. The side opposite the right angle is called the hypotenuse, and it is always the longest side of the triangle.
The other two sides are called the legs or the perpendicular sides.
How is a right triangle calculated?
The Pythagorean theorem can be used to find a missing side of a right triangle when the other two sides are known. Basic trigonometric functions can also be used to determine the two acute angles.
The calculator uses the values you enter to determine the requested measurement and displays the calculation using your actual numbers.
Right triangle calculator example
Suppose the two legs of a right triangle are 3 meters and 4 meters.
c = √(3² + 4²)
c = √(9 + 16)
c = √25
c = 5 m
Therefore, the hypotenuse is 5 meters.
Formula used
a² + b² = c²
Hypotenuse:
c = √(a² + b²)
Missing leg:
a = √(c² − b²)
Area:
Area = ½ × a × b
Angle A:
A = tan⁻¹(a ÷ b)
Angle B:
B = 90° − A
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Important: This calculator is provided for general informational and educational purposes only. The results are based on the values entered and standard mathematical formulas. Always verify important measurements and calculations independently when accuracy is critical.