Example
The graph of the
Cartesian equation xy = 1 is a hyperbola with two asymptotes.
If the equation
is written as y = 1/x we see that y
approaches 0
as  x  becomes arbitrarily large, so part of the hyperbola
approaches the x axis asymptotically.
If the equation
is written as x = 1/y we see that x
approaches 0 as  y  becomes arbitrarily large, so part
of the hyperbola approaches the y axis asymptotically.
