From the given map, as we can see that the Birch street is a horizontal line, so the slop of the Birch street is 0.
So for the Elm street to be perpendicular to Birch street, it must have
an undefined slope, that is a vertical line.
but from the map we can see that the slope of the Elm street is not
as a slope of a vertical line.Hence the Birch street and Elm street are not perpendicular
