# NCERT Class 9 Mathematics Chapter 1 Orienting Yourself: The Use of Coordinates: Summary, Concepts, and Revision Notes | SwaVid

This chapter introduces the fundamental concept of coordinate geometry, a powerful tool for locating points in a plane. Just as you might describe the l...

Canonical: https://swavid.com/maths/class/9/chapter/orienting-yourself-the-use-of-coordinates

Source: https://swavid.com/maths/class/9/chapter/orienting-yourself-the-use-of-coordinates

# Orienting Yourself: The Use of Coordinates

## Concepts in this chapter

## The ideas this chapter keeps returning to

## Where this chapter usually trips people up

## Find the gaps before this chapter finds them for you.

## Related chapters

### The Need for a Coordinate System

Chapter 1 · Class 9 Mathematics

This chapter introduces the fundamental concept of coordinate geometry, a powerful tool for locating points in a plane. Just as you might describe the location of a seat in a cinema hall using its row and column, or a house in a city using street names and house numbers, a coordinate system provides a precise way to specify any point's position using a pair of numbers. You will learn about the Cartesian system, which uses two perpendicular lines to create a map-like grid, allowing you to uniquely identify every point in a two-dimensional space.

Your study route

Key topics

To precisely locate an object or a point in a plane, a systematic method is required. Just like finding a seat in a cinema hall by its row and column number, or a house by its street and house number, a coordinate system provides a unique way to describe position.

Example

The chapter begins by illustrating the need for a system to locate a point, such as finding a specific seat in a cinema hall or a house in a city, which naturally leads to the idea of using two references.

Watch out

Children might not immediately grasp why two numbers are needed, thinking one might be enough. Emphasize that a single number only works on a line, not a flat surface.

To precisely locate an object or a point in a plane, a systematic method is required. Just like finding a seat in a cinema hall by its row and column number, or a house by its street and house number, a coordinate system provides a unique way to describe position.

Tap the card for an example

Example

The chapter begins by illustrating the need for a system to locate a point, such as finding a specific seat in a cinema hall or a house in a city, which naturally leads to the idea of using two references.

Why it matters

This concept is fundamental to mapping, navigation, computer graphics, and understanding relationships between variables in science and engineering. It allows us to translate geometric positions into numerical data.

Watch out

Children might not immediately grasp why two numbers are needed, thinking one might be enough. Emphasize that a single number only works on a line, not a flat surface.

Ask at home

Ask your child: 'If I tell you to find a point at '5', where would you look on a flat paper? What additional information would you need to find it precisely?'

Chapter 1, 'Orienting Yourself: The Use of Coordinates', lays the groundwork for understanding how to locate points in a plane. It introduces the Cartesian system, which consists of two perpendicular number lines: the horizontal X-axis and the vertical Y-axis. Their intersection point is called the origin. These axes divide the plane into four regions known as quadrants. Each point in this plane is uniquely identified by an ordered pair of numbers, (x, y), where 'x' is the x-coordinate (abscissa) and 'y' is the y-coordinate (ordinate). The chapter explains how to plot these points and understand the signs of coordinates in different quadrants. It also highlights the special cases of points lying on the axes and the importance of the order of coordinates, emphasizing that (x, y) is distinct from (y, x).

Chapter summary

Chapter 1, 'Orienting Yourself: The Use of Coordinates', lays the groundwork for understanding how to locate points in a plane. It introduces the Cartesian system, which consists of two perpendicular number lines: the horizontal X-axis and the vertical Y-axis. Their intersection point is called the origin. These axes divide the plane into four regions known as quadrants. Each point in this plane is uniquely identified by an ordered pair of numbers, (x, y), where 'x' is the x-coordinate (abscissa) and 'y' is the y-coordinate (ordinate). The chapter explains how to plot these points and understand the signs of coordinates in different quadrants. It also highlights the special cases of points lying on the axes and the importance of the order of coordinates, emphasizing that (x, y) is distinct from (y, x).

What you should learn

Keep these close

A coordinate system helps locate points in a plane using two numbers.

The Cartesian plane uses a horizontal X-axis and a vertical Y-axis.

The intersection of the X-axis and Y-axis is called the origin (0, 0).

The axes divide the plane into four quadrants, numbered I, II, III, IV anti-clockwise.

Each point is represented by an ordered pair (x, y).

The x-coordinate is called the abscissa, and the y-coordinate is called the ordinate.

To plot (x, y), move x units horizontally from the origin, then y units vertically.

Signs of coordinates in Quadrant I are (+,+).

Signs of coordinates in Quadrant II are (-,+).

Signs of coordinates in Quadrant III are (-,-).

Signs of coordinates in Quadrant IV are (+,-).

Points on the X-axis have coordinates (x, 0); points on the Y-axis have coordinates (0, y).

Common confusions

It is easy to think

Confusing the x-coordinate with the y-coordinate, leading to plotting (y, x) instead of (x, y).

The clearer idea

Always remember that the first number in the ordered pair (x, y) refers to the horizontal movement along the X-axis, and the second number refers to the vertical movement along the Y-axis. Think 'X before Y' alphabetically and in plotting.

It is easy to think

Incorrectly recalling the signs of coordinates for different quadrants, especially Quadrant II and IV.

The clearer idea

Visualize the axes: Right is positive X, Left is negative X. Up is positive Y, Down is negative Y. Then combine these for each quadrant: Q1 (Right, Up) = (+,+); Q2 (Left, Up) = (-,+); Q3 (Left, Down) = (-,-); Q4 (Right, Down) = (+,-).

It is easy to think

Believing that a point like (5, 0) lies on the Y-axis, or (0, -3) lies on the X-axis.

The clearer idea

If the y-coordinate is zero, the point lies on the X-axis (e.g., (5, 0) is 5 units right on the X-axis). If the x-coordinate is zero, the point lies on the Y-axis (e.g., (0, -3) is 3 units down on the Y-axis).

Before you push ahead

Most stuck chapters trace back to one earlier idea. Check the prerequisites first, or let SwaVid adapt this chapter to the way your child learns.

Keep exploring Class 9

Source

- Understand the necessity and utility of a coordinate system for locating points in a plane.
- Identify and define the X-axis, Y-axis, origin, and the four quadrants within the Cartesian plane.
- Explain the terms 'abscissa' and 'ordinate' and correctly write the coordinates of any given point.
- Accurately plot points on a Cartesian plane when their coordinates are provided.
- Determine the quadrant or axis in which a given point lies based on the signs and values of its coordinates.
- Understand the necessity and utility of a coordinate system for locating points in a plane.
- Identify and define the X-axis, Y-axis, origin, and the four quadrants within the Cartesian plane.
- Explain the terms 'abscissa' and 'ordinate' and correctly write the coordinates of any given point.
- Accurately plot points on a Cartesian plane when their coordinates are provided.
- Determine the quadrant or axis in which a given point lies based on the signs and values of its coordinates.
- NCERT Class 9 Mathematics textbook: Ganita Manjari : Chapter 1: Orienting Yourself: The Use of Coordinates

## Key Links

- [NCERT Mathematics](https://swavid.com/maths)
- [Class 9](https://swavid.com/maths/class/9)
- [Start with concepts](https://swavid.com/maths/class/9/chapter/orienting-yourself-the-use-of-coordinates)
- [Check a prerequisite](https://swavid.com/learning-debt-identifier)
- [Concepts](https://swavid.com/maths/class/9/chapter/orienting-yourself-the-use-of-coordinates)
- [Practice](https://swavid.com/maths/class/9/chapter/orienting-yourself-the-use-of-coordinates/practice-questions)
- [NCERT Solutions](https://swavid.com/maths/class/9/chapter/orienting-yourself-the-use-of-coordinates/ncert-solutions)
- [Find the gaps before this chapter](https://swavid.com/learning-debt-identifier)
- [Learn this chapter adapted to you](https://swavid.com/learning-style-test)
- [Next chapter 2 . Introduction to Linear Polynomials](https://swavid.com/maths/class/9/chapter/introduction-to-linear-polynomials)
- [All Class 9 chapters](https://swavid.com/maths/class/9)
- [2 Introduction to Linear Polynomials Polynomials: Definition and Terminology · Classification of Polynomials Open chapter](https://swavid.com/maths/class/9/chapter/introduction-to-linear-polynomials)
- [3 The World of Numbers Rational Numbers and their Decimal Expansions · Irrational Numbers Open chapter](https://swavid.com/maths/class/9/chapter/the-world-of-numbers)
- [4 Exploring Algebraic Identities Understanding Algebraic Identities · Identities for Squares and Binomial Products Open chapter](https://swavid.com/maths/class/9/chapter/exploring-algebraic-identities)
- [NCERT Class 9 Mathematics textbook: Ganita Manjari](https://ncert.nic.in/textbook/pdf/iemh101.pdf)