Rear Yard.
There shall be a rear yard not less than three (3) feet from any lot line, alley line or easement line, except that if no alley exists, the rear yard shall not be less than ten (10) feet as measured from the rear lot line. In residential districts the main building and all accessory buildings shall not cover more than fifty (50) percent of that portion of the lot lying to the rear of a line erected joining the midpoint of one side lot line with the midpoint of the opposite side lot line. Carports, garages, or other detached accessory buildings located within the rear portion of the lot as heretofore described shall not be located closer than fifteen (15) feet to the main building nor nearer than three (3) feet to any side lot line. (See appendix illustration 3)