Trigonometry
posted by Laurianne on .
When using the Law of Cosines, how do I know if two triangles exist?

You question makes no sense to me.

If it is a triangle, the law of cosines work.
There are cases where no triangle can exist with the given lengths or angles. For example if the sum of the two shorter sides is less than the long side or if the three angles do not add up to 180 degrees.