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Two dimensions. In the figure, three point particles are fixed in place in an xy plane. Particle A has mass ma = 4 g, particle B has mass 2.00mA, and particle C has mass 3.00mA. A fourth particle D, with mass 4.00mA, is to be placed near the other three particles. At what (a) x coordinate and (b) y coordinate should particle D be placed so that the net gravitational force on particle A from particles B, C, and D is zero (d = 21 cm)? 1.5d A