Scalene Triangle Calculator
Calculate area, perimeter and angles of a scalene triangle from three unequal sides.
About Scalene Triangle Calculator
A scalene triangle has three unequal sides. Area is computed via Heron's formula and angles via the law of cosines.
Formula
Law of Cosines
cos(A) = (b² + c² − a²) / (2bc)
- a
- Side opposite angle A
- b
- Second side
- c
- Third side
Worked example
With the default values below, Scalene Triangle Calculator returns Area of 31.4195. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Side aminimum 0 units
- 7 units
- Side bminimum 0 units
- 9 units
- Side cminimum 0 units
- 11 units
Results
- Area
- 31.4195 sq units
- Perimeter
- 27.0000 units
- Angle A
- 39.4006 °
- Angle B
- 54.6955 °
- Angle C
- 85.9040 °
Step by step
- 1Semi-perimeter
- 2Area (Heron's)= 31.4195
- 3Angle A (law of cosines)= 39.4006°
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
What makes a triangle scalene?
All three sides (and all three angles) are different. No two sides are equal.
Can a scalene triangle be right-angled?
Yes — a right triangle can be scalene if its three sides are all different, like the classic 3-4-5 triangle.