Question

This time I inserted the picture.

Answer 1

You use the law of cosines whenever you're given a SAS triangle. The formula is

$c^2=a^2+b^2-2ab\cos C$

C is the given angle, c is the side opposite this angle, and a/b are the given sides adjacent to angle C.

In this case, if $c$ is the length of the missing side, then

$c^2=9^2+6^2-2\cdot9\cdot6\cos37^\circ\implies c\approx7.66$