4
CBSE Marks
★★★★★
Difficulty
8
Topics
Medium
Board Weight
Topics Covered
8 key topics in this chapter
Cartesian System
Quadrants & Sign Conventions
Plotting Points in the Plane
x-axis, y-axis, Origin
Abscissa & Ordinate
Distance from Axes
Points on Axes
Graphs of Linear Equations in Two Variables
Study Resources
Key Formulas & Identities
| Formula / Rule | Expression |
|---|---|
| Point on x-axis | \((x, 0)\) |
| Point on y-axis | \((0, y)\) |
| Origin | \((0, 0)\) |
| Quadrant I | \((+, +)\) |
| Quadrant II | \((−, +)\) |
| Quadrant III | \((−, −)\) |
| Quadrant IV | \((+, −)\) |
| Reflection in x | \((x, y) → (x, −y)\) |
| Reflection in y | \((x, y) → (−x, y)\) |
Important Points to Remember
The x-coordinate (abscissa) of any point on the y-axis is 0. The y-coordinate (ordinate) of any point on the x-axis is 0.
The origin O has coordinates (0, 0). Quadrant signs: I(+,+), II(−,+), III(−,−), IV(+,−).
Mirror image in x-axis: (x, y) → (x, −y). Mirror image in y-axis: (x, y) → (−x, y). Mirror image in origin: (x, y) → (−x, −y).
At Class IX, the focus is on plotting and reading coordinates — no distance or section formula yet (those are in Class X).