Find a side of a triangle given other two sides and an angle I have a really simple-looking question, but I have no clue how I can go about solving it?
The question is 

Find the exact value of $x$ in the following diagram:


Sorry for the silly/easy question, but I'm quite stuck! To use the cosine or sine rule, I'd need the angle opposite $x$, but I can't find that, cause I don't have anything else to help it along.
Thank You!

Actually,you can use the Law of Cosine as follows:
$$
\rm{Cos}\,60^{\circ}=\frac{6^2+x^2-7^2}{2\times6\times x},
$$
Then you can easily find out that $x=3+\sqrt{22}$.
