Chapter 03 Coordinate Geometry Exercise-01
EXERCISE 3.1
1. How will you describe the position of a table lamp on your study table to another person?
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Solution
Consider that the lamp is placed on the table. Choose two adjacent edges, DC and AD. Then, draw perpendiculars on the edges $D C$ and $A D$ from the position of lamp and measure the lengths of these perpendiculars. Let the length of these perpendiculars be $30 cm$ and $20 cm$ respectively. Now, the position of the lamp from the left edge (AD) is $20 cm$ and from the lower edge (DC) is $30 cm$. This can also be written as (20, $30)$, where 20 represents the perpendicular distance of the lamp from edge AD and 30 represents the perpendicular distance of the lamp from edge DC.
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 $200 \mathrm{~m}$ apart. There are 5 streets in each direction. Using $1 \mathrm{~cm}=200 \mathrm{~m}$, 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 $2^{\text {nd }}$ street running in the North - South direction and $5^{\text {th }}$ 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 $(3,4)$.
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Solution
Both the cross-streets are marked in the above figure. It can be observed that there is only one cross-street which can be referred as $(4,3)$, and again, only one which can be referred as $(3,4)$.
