Page 139 - Math Skill - 4

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Here, MN || OP and AB || CD. M N D

We can see parallel lines in a zebra crossing, the B
lines in notebook O P C
and in railway tracks around us. A

Intersecting lines: The lines that cross each
other at a point are called intersecting lines. A D
Here, two lines AB and CD intersect at Fact-o-meter
point M. M Symbol ‘||’ is used to
show ‘is parallel to’.
And point ‘M’ is called an intersecting point. C B

Measuring Line Segments

Line segments can be measured using ‘a ruler’ or commonly called ‘scale’. One edge of a ruler
is marked in ‘centimetres’ (cm) and other edge in ‘inches’.
P Q

P Q

We measure line segments in centimetres and, as shown above, each centimetre is divided into
10 equal small divisions. Each small division is called a ‘millimetre’ (mm). Thus, 1 cm = 10 mm.
Let us take a line segment PQ and measure its length.
Place the edge of the ruler along line segment PQ, keeping the 0 (zero) centimetre mark at P.
Read the mark on the ruler at the point Q. Fact-o-meter

Since Q coincides with 5.5. � One and only one line can be drawn
Hence, PQ = 5.5 cm. passing through two fixed points.

Thus, the length of the line segment PQ is 5.5 cm. � An unlimited number of lines can
pass through a single point.
Drawing a Line Segment of Given Length

To draw a line segment of any given length (say 3.8 cm), we follow these steps:

Step 1: Place the ruler on the sheet or your notebook and hold it firmly.
Step 2: Mark a point at 0 (zero) with a finely sharpened pencil and then mark a point at 3.8 cm.
Step 3: Slide the pencil gently along the edge of the ruler from 0 to 3.8 cm without moving the
ruler.
Step 4: Name the line segment as AB.

A B

AB = 3.8 cm

Thus, we have drawn a line segment AB of length 3.8 cm.