Class 9 · Mathematics · New NCERT
Chapter 1: Orienting Yourself: The Use of Coordinates
Chapter 1 introduces the Cartesian plane: a pair of perpendicular number lines (the x-axis and y-axis) that give every point in a plane a unique address as an ordered pair of coordinates. Using a floor plan of a room, a house and a city block as running examples, the chapter develops the distance formula and the midpoint formula, and uses them to check whether points are collinear, to identify shapes such as squares and trapeziums from their vertices, and to work out spacing, widths and areas from coordinates alone.
Topics covered
- The Cartesian plane, axes, origin and quadrants
- Plotting points from an ordered pair of coordinates
- The distance formula
- The midpoint formula
- Testing whether three points are collinear
- Identifying shapes (squares, trapeziums, triangles) from vertex coordinates