1. The problem statement, all variables and given/known data The charges and coordinates of two charged particles held fixed in an xy plane are q1 = +3.0 microCoulombs, x1 = 3.5cm, y1 = 0.50cm, and q2 = -4.0 microCoulombs, x2 = 2.0cm, y2 = 1.5cm. Find the (a) magnitude and (b) direction of the electrostatic force on particle 2 due to particle 1. At what (c) x and (d) y coordinates should a third particle of charge q3 = +4.0 microCoulombs be placed such that the net electrostatic force on particle 3 due to particles 1 and 2 is zero? 2. Relevant equations Herein lies the problem. Other than kq1q2/r^2 (Coulomb's Law), I'm not sure how to approach this. 3. The attempt at a solution I've tried the method I remember from previous Physics, which is to add x1 + x2 for a net X and y1 + y2 for a net Y, then taking the square root of Xnet^2 + Ynet^2 for the magnitude, and the arctangent of Ynet over Xnet for the angle, which get me some answers, but I'm not sure if this is the proper method to use for parts a and b. I am also unclear on how to even begin parts c and d other than the observation that F31 + F32 must equal zero. Any help or hints at how to get started would be appreciated.