AllEasyToolsMathematics
Triangle from sides
Triangle from sides: calculate from your inputs and inspect the formula. No account required. Processing stays in your browser.
s=(a+b+c)/2; A=√[s(s−a)(s−b)(s−c)]
Check units and the formula domain. Numerical results are rounded.
How to use this calculator
- Identify the quantities and convert them to the units shown.
- Apply the formula first, then compare with the substitution and result.
- Check the assumptions and whether the order of magnitude makes sense.
Levels are approximate topic groupings, not a complete curriculum for every country. Numerical results are rounded and may lose precision for extreme or nearly singular inputs.
A practical example
Use these sample inputs to check the calculation before entering your own values.
- Side a
- 3
- Side b
- 4
- Side c
- 5
Result for this example
- Perimeter
- 12
- Area
- 6
- Angle opposite a
- 36.86989764584401 °