Find sides and height of isosceles trapezium given information about its diagonals 
In an isosceles trapezium  the diagonals cut at a point $O$ which divides them in two segments of $3$ cm and $7$ cm. If one of the angles formed between them is of $120°$, find the measures of the sides and the height of the trapezium. 

I am stuck at this problem. I've made a picture and from the drawing I could see that the other angle is of $60°$. The two diagonals divide the trapezium in four triangles, each of which I have the measure of two of its sides. What else can I think of two figure out the measures of the sides? I would really appreciate suggestions. Thanks in advance.

The Law of Cosine will enable you to find the sides.
