1. The problem statement, all variables and given/known data Given a parallelogram ABCD has vertices A(-1,2,-1), B(2,-1,3) and D(-3,1-3). Find the coordinates of C. 2. Relevant equations 3. The attempt at a solution I'm extremely confused here. I do not know how to tell which coordinate is for which vertex on the parallelogram. I know this has to do with vector addition, but I can't picture it to solve the problem.