It can be observed that, x + y + z + w then prove that AOB is a line.
\(⇒\)\(\text{ x+y+w+z = 360°}\)
It is given that,
\(\text{x+y = w+z}\)
So, (x + y) +(x + y) = 360°
2(x + y) = 360°
∴ (x + y) = 180°
Since x and y form a linear pair, AOB is a line.
(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).