Coordinates (Four Quadrants)
Coordinates in four quadrants extend the basic coordinate system by introducing negative values for both x and y axes. The coordinate plane divides into four regions: Quadrant I contains points with positive x and y values, Quadrant II has negative x and positive y, Quadrant III has negative x and negative y, and Quadrant IV has positive x and negative y. This system appears in Year 6 of the UK National Curriculum, where pupils describe positions on the full coordinate grid.
Why it matters
Four-quadrant coordinates appear throughout GCSE mathematics, particularly in algebraic graphs where functions like y = x² - 4 cross into negative regions. Navigation systems use similar principles — GPS coordinates include negative values for locations south of the equator or west of the prime meridian. Temperature graphs plotting data below 0°C require negative y-values, whilst profit-loss charts in business studies use negative coordinates to show losses. Computer graphics and game programming rely heavily on four-quadrant systems for positioning objects. Weather maps showing temperature changes across regions frequently display data points in multiple quadrants. The concept prepares students for advanced topics like transformations, where reflections across axes change coordinate signs, and gradient calculations between points in different quadrants.
How to solve coordinates (four quadrants)
Coordinates — Four Quadrants
- Quadrant I: (+, +). Quadrant II: (−, +).
- Quadrant III: (−, −). Quadrant IV: (+, −).
- Negative x = left of origin; negative y = below origin.
- Plot points by moving along x first, then y.
Example: (−2, 3) is in Quadrant II: 2 left, 3 up.
Worked examples
In which quadrant is the point (-4, 6)?
Answer: Quadrant II
- Check signs of x and y → x = -4 (negative), y = 6 (positive) — Quadrant II: x is negative, y is positive.
What are the coordinates after reflecting (4, 5) in the x-axis?
Answer: (4, -5)
- Reflect in the x-axis → (4, -5) — Reflecting in the x-axis negates the y-coordinate.
Find the distance between (-8, 7) and (7, 7).
Answer: 15
- Subtract x-coordinates (same y) → |7 - (-8)| = |15| = 15 — Distance on a horizontal line = absolute difference of x-coordinates.
Common mistakes
- Confusing quadrant numbers with coordinate signs — writing that (-3, 2) is in Quadrant III instead of Quadrant II because the x-coordinate is negative
- Mixing up reflection rules — reflecting (4, 5) across the y-axis as (4, -5) instead of (-4, 5), incorrectly changing the y-coordinate rather than the x-coordinate
- Calculating distance between (-6, 3) and (2, 3) as 4 instead of 8, forgetting that movement from negative to positive coordinates requires adding the absolute values