The triangular area referred to in Section 8.79.020 shall be formed as follows: one angle of the triangle shall be formed by the front and side lot lines of each corner lot; the sides of such triangle shall be a minimum of twenty feet in length, measured from the corner angle formed by the intersection of the front and side lot lines; the third side of the triangle shall be a straight line connecting the last two mentioned points. In the case of rounded corners, the triangular area between the tangents to the curve and a diagonal line joining points on said tangents twenty feet from the point of their intersection. The tangents referred to are those at the beginning and at the end of the curve at the corner. (Ord. 481,, 1972.)