Cartesian plane
Coordinates and ordered pairs
The Cartesian plane is formed by two perpendicular number lines: the horizontal \(x\)-axis and the vertical \(y\)-axis. Their intersection is the origin \((0,0)\).
A point is written as an ordered pair \((x,y)\). The first coordinate tells us how far to move horizontally, and the second coordinate tells us how far to move vertically.
Quadrants
The axes divide the plane into four quadrants. The signs of the coordinates are \((+,+)\) in quadrant I, \((-,+)\) in quadrant II, \((-,-)\) in quadrant III and \((+,-)\) in quadrant IV.
Practice
Read the ordered pairs shown in the GeoGebra activity. Drag points A, B, C and D to the corresponding positions in the Cartesian plane and use the controls included in the applet to check your answer or generate a new exercise.
Useful strategy
Always read an ordered pair in the same order: first \(x\), then \(y\). A positive \(x\) moves to the right, a negative \(x\) to the left; a positive \(y\) moves up, and a negative \(y\) moves down.