Triangle Calculator
Enter the three side lengths to compute the area (using Heron's formula), perimeter and all three interior angles (via the law of cosines).
Triangle Calculator
MathArea, perimeter & angles from three sides.
Triangle (3 sides)
3
4
5
Area
6
- Perimeter
- 12
- Angle A
- 36.87°
- Angle B
- 53.13°
- Angle C
- 90°
- Area
- 6
Frequently asked questions
What is Heron's formula?
With semi-perimeter s = (a+b+c)/2, the area = √(s(s−a)(s−b)(s−c)). It gives the area from the three side lengths alone.
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