Triangle Solver (SSS, SAS, ASA, AAS)
Solve any triangle from three known parts using the Laws of Sines and Cosines.
Inputs
Enter any 3 of 6 values
Solution
Enter values and click solve.
How it solves
To solve a triangle you need at least three pieces of information, and at least one of them must be a side. The four common cases are SSS, SAS, ASA, and AAS.
This calculator uses the Law of Cosines to handle SSS and SAS, and the Law of Sines for ASA/AAS.
Frequently Asked Questions
How many values do I need to enter?▾
At least three values, and at least one must be a side. Three angles alone don't determine a unique triangle.
What are SSS, SAS, ASA, and AAS?▾
Side-Side-Side, Side-Angle-Side, Angle-Side-Angle, Angle-Angle-Side. Each describes a different combination of known parts.
Which method does the solver use?▾
It picks Law of Cosines for SSS and SAS, and Law of Sines for ASA and AAS. The two laws together cover every solvable case.
Why might my inputs return an error?▾
Either the triangle inequality is violated, your angles don't sum to less than 180°, or the data is ambiguous (SSA case).