Page 337 - Start Up Mathematics_8 (Non CCE)

Activity Time (in hours) Central angle

Study in school   × 360   ° = __________°
 24 

Do homework   × 360   ° = __________°
 24 

Play games   × 360   ° = __________°
 24 

Sleep   × 360   ° = __________°
 24 

Watch TV   × 360   ° = __________°
 24 

Others   × 360   ° = __________°
 24 
Total 24 360°
Observations:
1. The activity on which maximum time is spent is ______________.
2. The activity on which minimum time is spent is ______________.

Introduction to Line Graphs

In your earlier classes you have learnt to represent numbers (both positive and negative) on a number line.

–4 –3 –2 –1 0 1 2 3 4

The positive numbers are to the right of 0 and the negative
numbers are to the left of 0. Y
It is not always possible to use a number line to locate the
position of a point. To overcome this we have two number 4
lines perpendicular to each other intersecting at 0. 3
2
Name the horizontal line as X¢OX and vertical line as
Y¢OY where O is point 0. These lines are called coordinate 1 O(origin)
axes. The line X¢OX is called the X-axis, the line Y¢OY is X’ –3 –2 –1 0 1 2 3 X
called the Y-axis and O is called the origin. The plane of –1
the paper containing both the axes is called the cartesian –2
plane or coordinate plane. –3
–4
l On the X-axis, i.e., X¢OX, OX denotes the positive part
and OX¢ the negative part. Y’
l On the Y-axis, i.e., Y¢OY, OY denotes the positive part
and OY¢ the negative part.
Remember
Ordered Pairs: A pair of two numbers x and y, listed in a specific order, is
called an ordered pair (x, y) with x at the first place and y at the second place. (x, y) ≠ (y, x)

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