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Triangle Calculator

Solve a triangle from three known sides and angles.

Enter any three (at least one side)

Each angle faces the side with the same letter.

Result

AreaExample

6

Right, scalene

Sides
a = 3, b = 4, c = 5
Angles
A = 36.869898°, B = 53.130102°, C = 90°
Perimeter
12
Heights to a, b, c
4, 3, 2.4
Inradius and circumradius
1 and 2.5

Runs on your device.

Questions

Which three values do I need?

Any three of the sides a, b, c and angles A, B, C, with at least one side: three sides, two sides and an angle, or one side and two angles.

Why are there sometimes two answers?

Two sides and an angle that isn’t between them can form two different triangles, the “ambiguous case”. Both are shown.

Which formulas are used?

The law of cosines (c² = a² + b² − 2ab cos C) and the law of sines (a ÷ sin A = b ÷ sin B = c ÷ sin C), and Heron’s formula for the area.

Is it free? Do I need an account?

It is free to use and there is nothing to sign up for. There are no watermarks and no daily limits.

Missing something, or not working as it should? Tell us