I'm studying electric field lines, and I'm doing the equation where you have to figure out the instantaneous electrostatic force of a certain object. However, I'm having trouble adding angles. Can someone help me?

Question

I'm studying electric field lines, and I'm doing the equation where you have to figure out the instantaneous electrostatic force of a certain object.  However,  I'm having trouble adding angles.  Can someone help me?

anonymous · Answer

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The drawing above is what i'm working on. My book says "Let's define the angles properly. Vector angles are always defined counterclockwise from the positive x-axis." But I don't know what that means:(