Class 9 Mathematics Chapter 1 Orienting Yourself: The Use of Coordinates – Revision Notes

Quick revision notes for Class 9 Maths Chapter 1 (Orienting Yourself: The Use of Coordinates). These Class 9 Mathematics Chapter 1 notes are ideal for quick revision just before exams.

Cartesian Plane

• x-axis (horizontal) + y-axis (vertical), meet at origin (0,0).
• 4 Quadrants, numbered I-IV anticlockwise from top-right.

Coordinates

• Point = (x, y); x = abscissa, y = ordinate.
• Order matters: (a,b) ≠ (b,a) unless a=b.

Sign Convention

• QI (+,+); QII (−,+); QIII (−,−); QIV (+,−).
• On x-axis: y=0. On y-axis: x=0.

One-Line Summary

The Cartesian plane locates any point using an ordered pair of coordinates (x,y), with sign patterns identifying the quadrant, forming the foundation for coordinate geometry.

Written by Satish

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