# Section 6: Basic Coordinate Geometry

Points on a coordinate plane
A coordinate plane is often very useful for writing linear equations with two variables. The coordinate plane is formed by a horizontal axis (x-axis) and a vertical axis (y-axis). The two axes intersect at a point called the origin. Points are plotted on a coordinate plane using a set of ordered pairs (x,y.) The first number in the ordered pair indicates how many spaces to move along the x-axis and the second number in the ordered pair indicates how many spaces to move along the y-axis.

Example: Write the coordinates of the point shown on the coordinate plane.

Because the point is located 4 units right along the x-axis, the x-value of the point is 4. Because the point is located 1 unit up along the y-axis, the y-value of the point is 1. Therefore, the x, y coordinates of the point are (4,1.) Note: points along the x-axis to the left of the origin are negative and points along the y-axis below the origin are negative.