NCERT Class 9 Solutions: Coordinate Geometry (Chapter 3) Exercise 3.1 – Part 1

Q-1. How will you describe the position of table lame on your study table to another person?

Sol:

  • Consider the lamp as a point P and table as a plane.

  • Choose any two perpendicular edges of the table, say OX and OY.

  • Measure the distance of the lamp i.e, P from the longer edge OX, let it be 1cm. Again, measure the distance of the lamp P from the shorter edge OY, let it be 2cm.

    Given the position of table lamp on your study table to another person in figure

    Given the Position of Table Lamp on Your Study Table

    Given the position of table lamp on your study table to another person in figure

  • So, the position of the lamp P referred to the edges OX and OY is (2,1).

Q-2. (Street Plan) : A city has two main roads which cross each other at the centre 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 this road and are 200m apart. There are about 5 streets in each direction. Using 1cm = 200m, draw a model of the city on your notebook. Represent the road/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:

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

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

Sol:

  • A city has two main roads which cross each other at the centre of the city. These two roads are along the North-South direction and East-West direction.

  • There are about 5 streets in each direction. We draw a diagram using 1cm = 200m

    Streets in the blocks treated as a grid

    Streets in a Block

    Streets in the blocks treated as a grid

  • A particular cross-street is made by two streets, one running in the North-South direction and another in the East-West direction.

  • The 2nd street running in the North-South direction and 5th in the East-West direction.

  1. Sol : Only one street can be referred to as (4, 3) as we see from the figure.

  2. Sol: Only one street can be referred to as (3, 4) as we see from the figure.

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