Coordinate (1,-2), angle of intersection thru origin?

[bchandler]

I'm trying to do a simple electric field due to point charges problem, but I'm stuck on a very simple detail. There are a number of point charges on an xy plane, and one of the point charges is at the cooridinate (1,-2). I need to figure out which angle a line drawn from this point to the origin would make with the x-axis to do the problem, but can't figure it out! I'm sure as soon as someone tells me the answer I'll remember how to find it; it's just a simple geometry problem!

Can anyone help? I can do the rest of the problem, its just this one snag that has me held up.

 

[bchandler]

Nevermind, I figured it out. I just set up a triangle along the axes to figure out the angle and the distance. Should have thought about this one more... Feel free to delete mods...