Y-axis
In coordinate
geometry the term 'y-axis' usually refers to a
vertical number line. This number line works just like the x-axis number
line, except its extent runs vertically with values increasing upward. That
is, positive values become greater as one moves up the y-axis from zero, the
origin, and negative values become less as one moves down from zero. This is
shown on the following diagram.
The y-axis extends to negative infinity below and to positive infinity above.
A point on the y-axis has both a coordinate and a name. The coordinate is the value on the number line where the point is located. The name is usually a letter. Here we will use the name 'y' for a point on the y-axis.
