On a corner lot in any residential district, nothing shall be erected, placed, planted, or allowed to grow in a manner which obstructs vision higher than three feet (3') above the curb level at the street intersection, provided that this restriction shall not apply to shade trees, the entire foliage of which is eight feet (8') above the height of the curb. This restriction on sight obstruction shall apply to the triangular area formed by the two (2) streets rights-of-way adjoining the lot and a line drawn across the lot adjoining points on each right-of-way twenty feet (20') from the intersection of the right-of-way lines. (Ord. 925)