Coordinates Of A Point
The coordinates of a point are a pair of numbers that define its exact location on a two-dimensional plane. We already know that the coordinate plane has two axes at right angles to each other, called the x and y axis. The coordinates of a given point represent how far along each axis the point is located.
The coordinates are written as an "ordered pair".
The letter P is simply the name of the point and is used to distinguish it from others. The two numbers in parentheses are the x and y coordinate of the point.
1. The first number (x) specifies how far along the x (horizontal) axis the point is.
2. The second is the y coordinate and specifies how far up or down the y axis to go.
The sign of the coordinate is important. A positive number means to go to the right (x) or up (y). Negative numbers mean to go left on x axis or down to the y axis
Each point on a number line is assigned a number. In the same way, each point in a plane is assigned a pair of numbers.
The x‐axis and y‐axis separate the coordinate plane into four regions called quadrants.
- The upper right quadrant is quadrant I
- The upper left quadrant is quadrant II
- The lower left quadrant is quadrant III
- The lower right quadrant is quadrant IV.
The number to the left of the comma in an ordered pair is the x‐coordinate of the point and indicates the amount of movement along the x‐axis from the origin. The movement is to the right if the number is positive and to the left if the number is negative.
The number to the right of the comma in an ordered pair is the y‐coordinate of the point and indicates the amount of movement perpendicular to the x‐axis. The movement is above the x‐axis if the number is positive and below the x‐axis if the number is negative.