1. The problem statement, all variables and given/known data Is there an equation in which I can find the area of a quadrilateral when I know the length of three of the sides and 2 of the angles? Also I really need to find the measurement of the other two angles. 2. Relevant equations I know the cos and sin formulas of triangles, and may be I can use that but I do not know how to start The lengths I know are 15, 12 & 2 and the angles I know are 120 degrees between the 12 and 2 and 120 degrees between the 15 and the side I don't know. 3. The attempt at a solution I really need a nudge to start.. this is a small portion of a much bigger problem.