Click here only if you're in doubt about this.

Points on the y-axis look like [Graphics:projectionsgr41.gif]. The distance between [Graphics:projectionsgr42.gif] and [Graphics:projectionsgr43.gif] is

[Graphics:projectionsgr5.gif][Graphics:projectionsgr44.gif]
[Graphics:projectionsgr5.gif][Graphics:projectionsgr45.gif]

This distance is as small as it can be when [Graphics:projectionsgr46.gif].
This says that [Graphics:projectionsgr47.gif] is the point on the y-axis closest to [Graphics:projectionsgr48.gif].