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Triangle Calculator

SSS triangle: Heron area, perimeter, all three angles, side class, and acute/right/obtuse.

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Results

How to use Triangle Calculator

  1. Enter side a, side b, side c. Leave a field blank only when the page says the value is missing.
  2. Read the result rows under the form. Errors appear in the status line. Nothing is uploaded.
  3. Rounding follows IEEE floating point in this browser unless the page says it uses integers or BigInt.

Triangle Calculator

Heron area

ComputesSSS triangle: Heron area, perimeter, all three angles, side class, and acute/right/obtuse.
IncludesHeron area
IncludesAngles
IncludesClassification
Enginegeometry
UploadNone
AdviceArithmetic only

What Triangle Calculator is

Inequality: a+b>c and cyclic. Area = √(s(s−a)(s−b)(s−c)). Angles from the law of cosines in degrees. 3-4-5 is right and scalene.

The formula runs in this tab. CZNull does not receive the numbers.

How this page computes

Right triangles with a missing side can use Pythagoras directly.

Entities and related jobs

SSS triangle: Heron area, perimeter, all three angles, side class, and acute/right/obtuse. Named features: Heron area, Angles, Classification.

See also Pythagorean Theorem Calculator, Circle Calculator, Rectangle Calculator.

Use cases

Plots, trusses, and school SSS cases. SAS/ASA solvers are not on this page; enter three sides.

Limits

Invalid input appears in the status line. IEEE floating point applies unless a row says otherwise. CZNull does not receive the numbers.

Triangle Calculator questions

Does this page upload my numbers?
No. The formula runs in the page you opened. CZNull does not receive the values.
What does Triangle Calculator compute?
Inequality: a+b>c and cyclic.
Why is this its own URL?
Search queries name this job. Nearby modes stay on their own pages so inputs do not mix. Related calculators are linked below Triangle Calculator.
Area of 3-4-5?
6.
SAS or ASA?
Not on this page. Enter three sides.
Can I treat the result as official?
No. Rounding and real-world rules can differ. Use the page to check the arithmetic.