Sign up ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

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.


share|cite|improve this question
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

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.