Math & Statistics
Triangle Solver Calculator
Updated Sep 3, 2026 Reviewed Sep 3, 2026
Solve SSS, SAS, ASA, AAS, or SSA triangles for every side and angle plus perimeter, area, altitudes, inradius, circumradius, and ambiguous solutions.
Complete triangle geometry
Choose known measurements
Result
Calculation summary
Enter values to see the result
Your result, breakdown, assumptions, and warnings will appear here.
Scaled geometry
Triangle preview
How to use this calculator
- 1Choose the pattern matching known measurements.
- 2Enter the displayed sides and angles.
- 3Inspect every valid solution, especially for SSA.
Formula
c² = a² + b² − 2ab cos(C); a/sin(A) = b/sin(B) = c/sin(C)
The laws of cosines and sines solve the triangle; Heron’s formula finds area.
Calculation steps
- Validate sides, angles, and triangle inequalities.
- Solve remaining measurements for the selected case.
- Calculate area, radii, and altitudes.
Worked example
Sides 3, 4, and 5 form a right triangle with area 6 and perimeter 12.
Assumptions
- Side a is opposite angle A.
- Angles use degrees.
- SSA can have zero, one, or two solutions.
Sources
Frequently asked questions
Why can SSA have two answers?
Supplementary angles can share the same sine.
What is triangle inequality?
Any two sides must sum to more than the third.
Is the diagram exact?
It is scaled from solved geometry for explanation.
Which side matches A?
Side a is opposite angle A.
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