The distance between two point in the cartesian coordinate system is:
d^2=(x2-x1)^2+(y2-y1)^2
d^2=(1-1)^2+(18--4)^2
d^2=0+484
d=22 units.
In this case we could have seen that the x coordinate did not change and just said the distance was 18--4=22 units, but that is rarely how you will solve these problems :P
