For each of the 3 vectors you are given r and
First of all, convert them back to cartesian co-ordinates.
You need to say the from where you are measuring the angle. If you measure it from the x direction, you'll need 180 - 8.6 = 171.4 and since it is anticlockwise, you say that it's -171.4 degrees from the x axis.
I got slightly different answers. (20.0 N for magnitude and 8.7 degrees in your answer. Maybe you rounded off your numbers?)
But I think it's okay.