Triangle Calculator
Find area, angles and radii of a triangle from its three sides. The result updates as you type, with the working underneath so you can check it.
Your details
Result
Area
14.6969
Scalene triangle
- Perimeter
- 18
- Angle A
- 44.42°
- Angle B
- 57.12°
- Angle C
- 78.46°
- Inradius
- 1.63299
- Circumradius
- 3.57217
Good to know: Area = √(s(s−a)(s−b)(s−c))
About this tool
Formula
Area = √(s(s−a)(s−b)(s−c))
Questions people ask
How do I know three sides form a triangle?
Each side must be shorter than the sum of the other two (the triangle inequality).
Related tools
- Pythagorean Theorem CalculatorFind a missing side of a right triangle.
- Circle CalculatorFind area, circumference, radius and diameter from any one of them.
- Slope CalculatorFind slope, distance, midpoint and the line equation between two points.
- Quadratic Formula CalculatorSolve ax² + bx + c = 0, including complex roots and the vertex.
How we calculate this
We use the standard published formula or definition for this calculation, and we show the working so you can check it.
Spotted a mistake? Tell us and we'll check it. How we check our calculators