Class 9 Maths

Coordinate Geometry

Important Points:

If x ≠ y, then (x, y) ≠ (y, x), and (x, y) = (y, x), if x = y.

Quadrants and Coordinates

The best example of coordinates in everyday life is use of longitude and latitude on globe. Each unique location on the earth has a unique combination of longitude and latitude. Global positioning system used by radio taxi operators also uses x,y coordinates to find exact location of a vehicle.

Exercise 3.1

Question 1: How will you describe the position of a table lamp on your study table to another person?

Answer: I will say that the table lamp is at a distance of 10 inches from the left side of the table and 6 inches from the front side of the table.

Question 2: (Street Plan): A city has two main roads which cross each other at the center of the city. These two roads are along the North-South direction and East-West direction. All other streets of the city run parallel to these roads and are 200 m apart. There are about 5 streets in each direction. Using 1 cm = 200 m, draw a model of the city on your notebook. Represent the roads/streets by single lines.

There are many cross-streets in your model. A particular cross street is made by two streets, one running in the North-South direction and another in the East-West direction. Each cross-street is referred to in the following manner: If the 2nd street running in the North-South direction and 5th in the East-West direction meet at some crossing, then we will call this cross –street (2, 5). Using this convention, find:

Coordinate of Points

(a) How many cross-streets can be referred to as (4, 3).

Answer: Only one

(b) How many cross-streets can be referred to as (3, 4).

Answer: Only one