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A positive charge (red) is shown along with a region blocked by a gray curtain (position is given in meters). The electrostatic force on the positive charge is represented by a force vector. The region behind the gray curtain contains three charges of equal magnitude but unknown polarity (unknown sign). The charges are arranged in an equilateral triangle located around the center of the square. You can drag the red charge along the black circle. Restart.

Draw a picture indicating the sign and location of each charge within the covered area.

Problem authored by Melissa Dancy.