y-axis
Definition of y-axis

• The coordinate plane is formed by the intersection of two number lines, a horizontal number line and a vertical number line. The vertical number line is called the y-axis.

Examples of y-axis

• The figure shows the coordinate plane formed by the intersection of the x and y-axes. Their point of intersection is called the origin.

Solved Example on y-axis

Which of the following graphs has a point P on the y-axis?

Choices:
A.  Graph 1
B.  Graph 2
Correct Answer: A
Solution:
Step 1: The coordinate plane is formed by the intersection of two number lines, a horizontal number line and a vertical number line. The vertical number line is called the y-axis.
Step 2: Graph 1 has the point P on the vertical number line i.e., on the y-axis.

Related Terms for y-axis

• Coordinate Plane
• Number Line