A rectangle has a length of 2d and a height of d. Each of the following three charges is located at a corner of the rectangle:
  1. +q1 in the upper left corner
  2. +q2 in the lower right corner
  3. -q in the lower left corner.
The net electric field at the (empty) upper right corner iz zero. Find the magnitude of q1 and q2. Express your answers in terms of q.