Class 9 Maths Coordinate geometry-Ex-3.1

Coordinate geometry-Ex-3.1

Question 1:

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

Solution 1:

Let us consider the given below figure of a study stable, on which a study lamp is placed.

Class-9-Coordinate geometry-Ex-3.1

From the Figure Above,

  1. Consider the lamp on the table as a point
  2. Consider the table as a plane.
  3. We can conclude that the table is rectangular in shape, when observed from the top.

  • The table has a short edge and a long edge.
  • Let us measure the distance of the lamp from the shorter edge and the longer edge.
  • Let us assume
                          ▪Distance of the lamp from the shorter edge is 15 cm

                          ▪Distance of the lamp from the longer edge, its 25 cm.

Therefore, we can conclude that the position of the lamp on the table can be described in two ways depending on the order of the axes as (15, 25) or (25, 15).

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 the other streets of the city run parallel to these roads and are 200 m apart. There are 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:

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

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

Solution 2:

•Draw two perpendicular lines as the two main roads of the city that cross each other atthe center

•Mark it as N–S and E–W.

•Let us take the scale as 1 cm = 200 m.

•Draw five streets that are parallel to both the main roads, to get the given below figure.

Class-9-Coordinate geometry-Ex-3.1

Street plan is as shown in the figure:

(i)There is only one cross street, which can be referred as (4, 3).

(ii)There is only one cross street, which can be referred as (3, 4).