Area of quadrilateral knowing 3 sides and 2 angles

[j9mom]

Homework Statement

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.

Homework 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.

The Attempt at a Solution

I really need a nudge to start.. this is a small portion of a much bigger problem.

 

[Jebus_Chris]

Draw a picture. Find the area of the bottom trapezoid and top triangle then add them.

 

[j9mom]

OK, let me try that. I never thought of a trapezoid. Thanks.