How are angles in a right triangle calculated?

Using trigonometric ratios (sine, cosine, tangent) based on known side lengths.

What trigonometric ratio should I use?

SOH-CAH-TOA guides which ratio to use based on which sides are known.

Do the three angles always sum to 180°?

Yes — with one angle fixed at 90°, the other two must sum to 90°.

Right Triangle Angle Calculator - CalculatorLabs.net

Right Triangle Angle Calculator

A right triangle has one 90° angle, and once you know the two shorter sides (legs), you can find the hypotenuse and the two remaining angles using the Pythagorean theorem and basic trigonometry.

Leg a (opposite Angle A)

Leg b (opposite Angle B)

Instant Result

Hypotenuse (c) -

Angle A -

Angle B -

What Is a Right Triangle Angle & Side Solver?

A right triangle has one 90° angle, and once you know the two shorter sides (legs), you can find the hypotenuse and the two remaining angles using the Pythagorean theorem and basic trigonometry. This calculator solves the whole triangle instantly from the two legs.

How to Use This Right Triangle Angle & Side Solver

Measure the two legs of the right triangle (the two sides that form the 90° angle).
Enter leg a and leg b into the fields above.
Click Calculate to get the hypotenuse and both non-right angles.

Formula

Hypotenuse c = √(a² + b²)
Angle A = arctan(a / b)
Angle B = 90° − Angle A

Worked Example

A right triangle has legs of 6 cm and 8 cm. Hypotenuse = √(6² + 8²) = √100 = 10 cm. Angle A = arctan(6/8) ≈ 36.87°, and Angle B = 90 − 36.87 = 53.13°.