a = 4
b = 6
theta = 30
find the other sides/ angles
if $\displaystyle \theta$ is between sides $\displaystyle a$ and $\displaystyle b$, then you should be able to find side $\displaystyle c$ using a straight application of the law of cosines.
once you find side $\displaystyle c$, then use the law of sines to find another angle ... the third angle can be found using the fact that all three angles sum to 180 degrees.
let's see what you can do.