Question 72583
Tha is a very broad question, since we do not know where the variables are you are trying to solve. If the variable is one of the sides - you would use the Pythagoren Theorem; {{{a^2 + b^2 = c^2}}}
If it is one of the angles inside, you would add all angles to equal 180.
If you could maybe post a trianlge as an example, maybe we could answer better.