Class 9, Maths, Chapter 3, Exercise 3.1, Solutions
Q.1. How will you describe the position of a table lamp on your study table to another person?
Ans:
- Consider the lamp as a point P and table as a plane surface.
- Choose any two perpendicular edges of the table, let say OA and OB.
- Measure the distance of the lamp i.e., P from the longer edge OA, let it be 40 cm.
- Again, measure the distance of the lamp P from the shorter edge OB, let it be 30 cm.
- So, we can write the position of Lamp as (40,30).
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:
(i) How many cross – streets can be referred to as (4, 3).
(ii) How many cross – streets can be referred to as (3, 4).
Ans: 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)
