Page 55 - Maths Class 06

A line segment has length but no thickness. It contains two endpoints. Segment
Q
AB and segment BA are the same. Thus, a line segment is a portion of a line. The P
path from P to Q is called a curve.
Fig. 4.4

Ray

A ray is a part of a line which extends indefinitely in one direction from a point. A B
Here, AB is a ray with starting point A. It extends indefinitely in the Fig. 4.5
¾®
direction of arrowhead. It is represented as AB.

Oppo site Rays
In the Fig 4.6, OCand OD are two rays with the same initial point O and C O D
extending in opposite directions. They are called the opposite rays. Fig. 4.6

NOTE

A ray has one endpoint. A ray extends endlessly in one direction.
It cannot be measured. An infinite number of ray can be drawn from one point.
While naming a ray, starting point (initial point) is always written first.

Intersecting and Parallel Lines

Consider the top of a table, as shown in Fig. 4.7. The top has four edges, each edge A D
determines a line. Lines AB and BC intersect at B, whereas lines AD and BC do not
intersect at all.
B C
If two or more lines do not meet each other however far they are extended, then they
are called parallel lines.
Fig. 4.7
l 1
l
In Fig. 4.8 (a), the lines l and are intersecting lines. Then common point
1 2
is O. O
In Fig. 4.8 (b), the lines l and are parallel lines.
l
1 2 l
(a) 2
Are lines l and in Fig. 4.8 (b) intersecting lines?
l
1 2 l 1
No, because there is no common point.
Two lines that meet each other at a common point are called intersecting l 2
(b)
lines.
Fig. 4.8
Midpoint
A point on a line segment that divides the line segment into two equal portions is called its mid-point.
Dividing a line into two equal parts is also called bisecting. Therefore, the mid-point bisects a line.
In the adjoining line segment AB, C is the mid-point. It means point C

bisects line segment AB. Therefore, A C B
AC = BC or AC + BC = AB

55 Mathematics-6