In most cases complete triangles can be defined by only three elements. If you have three known parts (angles, sides, areas etc.) just type in the data and select the boxes. Unselect the elements whose quantities are unknown. The "special conditions"-box is mostly like a selected field when used.
Sometimes you only need two, sometimes possibly even four elements to describe a complete triangle. It depends on what kinds of elements are known. The calculator is not a magician, you have to give him enough, but not too much information.
Clicking on "Calculate Triangle" will fill up the grey boxes with the missing parts of the triangle (if the given data were consistent).
Note that in special cases same three elements fit to more than one triangle. The most common type of this is the definition by "angle-side-side". In case of ASS-ambiguities the calculator shows both solutions.
It is not always a good idea to calculate with q, p, Aq and Ap, when the angles α or β are greater than 90°. If your results are nonsense, turn the triangle until γ is the obtuse angle.
The "Special Conditions" box contains "greater than 90°" options. These options only make sense, when you have more than one solution. In ambiguous cases the triangle calculator usually takes angles smaller than 90° if possible.
A hidden feature of the triangle calculator is:
+ - * / can be used in the input fields to submit simple operations. For example 44.44*2 let the calculating program use the input value as 88.88. Only these four operators and only one per field will work.
The figures are not totally accurate, see them as illustrative figures. You can download them for private use, but you have to know that angles may differ several degrees from the real values.
Troubleshooting (a diagnosis of possible faults):