Triangle Calculator
Local ProcessingSolve triangles from sides and angles; perimeter, Heron’s area, laws of sines and cosines, equilateral and isosceles triangles.
How It Works & Processing Standards
Enter values above to calculate results automatically. Check each input field for guidance and units.
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Seven triangle calculations in one tool. Pick the one that matches what you know under "Calculation" and only the needed fields appear.
What You Can Do
- Solve from sides and angles
- SSS, SAS, ASA or AAS gives every remaining side and angle.
- Perimeter and Heron’s area
- Perimeter and area from three sides.
- Laws of sines and cosines
- Another side from a side and its opposite angle, or the third side from two sides and the included angle.
- Equilateral and isosceles
- Height, area and perimeter from one side (or the equal sides and base).
How to Use Triangle Calculator
- 1Choose a calculationPick what matches your known values. For solving, also pick the case (SSS etc.).
- 2Enter valuesSides in one unit, angles in degrees.
- 3Read the resultSides, angles and area in a table.
Examples
Common Use Cases
- Angles from three measured sides in surveying or woodworking
- The area of a triangular plot or panel
- Checking trigonometry homework
Frequently Asked Questions (FAQ)
What if the three sides cannot form a triangle?
If the longest side is at least the sum of the other two, it is not a triangle and you are told so.
What about SSA?
It can have two solutions, so the solver does not accept it. Use the law of sines to find one side at a time.