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Angle of a Right Triangle Calculator.

Calculate an acute angle and hypotenuse from the two legs of a right triangle.

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Set your values

Results update as you type.

Angle: 36.869898 °

Angle

36.869898°
Hypotenuse: 5 units

Hypotenuse

5.000000units

Results update automatically as you type.

Use Cases

Solve geometry homework problems

Quickly find missing angle and hypotenuse when given two legs of a right triangle, saving time on manual calculations.

Example: Given opposite = 3, adjacent = 4, the angle is about 36.87° and hypotenuse is 5.

Check construction or design measurements

Useful for verifying angles and diagonal lengths in projects involving right angles, such as framing or layout.

Example: If a ramp has a rise of 2 ft and a run of 6 ft, find the incline angle and ramp length.

Frequently Asked Questions

How do I use the Angle of a Right Triangle Calculator?
Enter the lengths of the opposite leg and the adjacent leg of a right triangle. The calculator will compute the acute angle (using inverse tangent) and the hypotenuse (using the Pythagorean theorem).
What is the formula used to find the angle?
The angle is found using the arctangent function: angle = arctan(opposite / adjacent). The result is given in degrees, representing the angle between the adjacent leg and the hypotenuse.
Can I use this calculator for any right triangle?
Yes, as long as you know the lengths of the two legs (opposite and adjacent) of a right triangle. The calculator will give you the acute angle and the hypotenuse for that triangle.

Tips & Common Mistakes

Tips

  • Ensure both leg lengths are positive numbers; zero or negative values will not produce valid results.
  • The calculator assumes the triangle is a right triangle, so the angle between the two legs is 90°.
  • The angle result is the acute angle opposite the 'opposite leg' you entered.
  • Use the same units for both legs (e.g., both in inches or both in centimeters) to get a consistent hypotenuse.

Common Mistakes to Avoid

  • Mixing up the opposite and adjacent legs relative to the angle you want to find.
  • Entering the hypotenuse as one of the legs; this calculator only accepts the two legs.
  • Forgetting to use consistent units, which can lead to incorrect hypotenuse values.

Last updated: August 13, 2026