**NCERT Solutions Class 9 Mathematics**

**Exercise 3.1**

**Q.1.** How will you describe the position of a table lamp on your study table to another person?

**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 these roads and are 200 m apart. There are 5 streets in each direction. Using, 1cm = 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:

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

**NCERT Solutions Class 9 Mathematics**

**Exercise 3.1**

**Q.1.** How will you describe the position of a table lamp on your study table to another person?

**Solution:**

** **To describe the position of a table lamp on the study table, we can take two mutually perpendicular sides of the table as X and Y axes. Take one corner of table as origin where both X and Y axes (sides) intersect each other. Drop two perpendiculars from this point on the two sides (i.e. X and Y axes). Measure the distance of the point from both X and Y axes and then write it in terms of coordinates, i.e. (x,y).

**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 these roads and are 200 m apart. There are 5 streets in each direction. Using, 1cm = 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:

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

**Solution:**

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