Problem: A charge of +18 uC is on the y axis at y = +3.0m. A charge of -12 uC is at the origin. Last, a charge of +45 uC is on the x axis at x = +3.0m. Determine the magnitude and direction of the net electrostatic force on the charge at x = +3.0mm. Specify the direction relative to the -x axis. So what I have drawn is: O-> 18 x (10)^-6 | | | /\ | 3.0m | \/ | | | | | Origin Charge: -12x10^-6 |O_ _ _ _ _ _ _ _ _ _ _ O -> 45 x (10)^-6 < 3.om > So I did: F1 = (8.99 x 10^9)(12 x 10^-6)(18 x 10^-6) / 9 = 1.942 N F2 = (8.99 x 10^9)(12 x 10^-6)(45 x 10^-6) / 9 = 0.539 N Can I use trig to determine the magnitude now? I tried it but I got this: 1.942cos90 = 0 1.942sin90 = 1 Surely I've messed up somewhere. Can someone point me in the right direction? Thanks a bunch!!