Page 37 - Ganit Kaushal

Some real-life examples of a ray are given below:

Beam of light from a lighthouse Ray of light from a torch Sun rays

Remember

• AB is the symbol used to represent a line segment joining A and B.

• AB is the symbol used to represent a line through A and B.

• AB is the symbol used to represent a ray with initial point A.
• AB is the symbol used to represent the length of the line segment joining A and B.
Intersecting Lines
l
m
Two lines are said to be intersecting if they have exactly one common point.
In the given figure, lines l and m intersect each other at a point P. In other words, the point P P
is the only point at which lines l and m meet. Here, point P is called the point of intersection
of the lines.

Parallel Lines

Parallel lines are those lines that go in the same direction and share no common point. l
Since there is no point at which they meet, they have no point of intersection. Parallel
lines remain apart at the same distance at all times (as shown in the adjacent figure). m
The symbol ‘| |’ is used to denote parallel lines. In the given figure,
lines l and m are parallel lines. So, they can be denoted as l | | m. Note
Two lines in a plane are
Concurrent Lines either intersecting or parallel.

Three or more lines are called concurrent, if all of them pass through one common point n
(called the point of concurrency). In the adjacent figure, lines l, m and n are concurrent O
lines and O is the point of concurrency. m
l
Solved Examples

Ex 1. From the adjacent figure, write n q p
(a) All pairs of parallel lines F
A B C l
(b) All pairs of intersecting lines
(c) Concurrent lines and point of concurrence D E m
(d) Collinear points

Lines and Angles 35