Find the direction of A= <-5,12>

I did arctan (12/-5) and added 180 because x was negative and got 105.13 degrees.

I missed the question on the test though. What did I do wrong?

3 answers

180+arctan(12/-5) = 112.6
Are you talking about the direction of the angle A from the origin to (-5,12) ?
I have never seen that notation before.

I agree with FredR's answer, if I interpreted the question correctly.
It could be interpreted as the azimuth, which in surveying applications is typically measured in a clockwise direction from north.