question is: Find the Cartesian coordinates corresponding to (4 pi/6) and polar coordinates corresponding to (-3, sqrt(3) )

i've attached some work to the problem,

ImageShack - Hosting :: untitledui2.png

however, is the tan-theta the answer then?

also, i'm confused where the 5pi/6 came from?

what part is where i can stop? which part is the answer?

thanks