# Determine the magnitude of the resultant

The two structural members, one of which is in tension and the other in compression, exert the indicated forces on joint O. Determine the magnitude R of the resultant R of the two forces and the angle θ which R makes with the positive x axis (measured counterclockwise from the x axis).

I have the resultant force but I don't know how to get theta.

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Do you have the $x$ and $y$ components of the resultant? If so, then just use $\theta=\arctan(y/x)$ –  Omnomnomnom Sep 4 '13 at 3:23
My x component is 3.81616. My Y component is -1.07517. When I use arctan(y/x) i get -15.7347. That answer is apparently incorrect. –  R3alAli Sep 4 '13 at 3:45
It could be that they want a positive angle. I'm not sure how many tries you have, but what about $360-15.7347=344.2653$? At any rate, you should definitely get an angle in the lower-right quadrant, so you can't be too far off the right track... –  Omnomnomnom Sep 4 '13 at 3:49
You were correct. Thanks for your help. –  R3alAli Sep 4 '13 at 4:05