x = r cosθ y = r sinθ
r = -3
θ = 120o
Plug them in a calculator and then write your answer as ( x, y).
If you are not able to use a calculator, then you will need to graph the line which will end up in Quadrant 4. If you create a right triangle with the line and the x-axis, you will get a 60o angle radiating from the origin. If you know your 30-60-90 triangle ratios you can find the lengths of the other sides which will tell you your x and y. I am sorry but it is very difficult to explain the graphing part without proper diagrams.