__Intersecting and Parallel Lines__

**If two lines have one common point, they are called intersecting
lines.**

**If there is a point P common to two lines and , then the two**

lines intersect at the point P and this

lines intersect at the point P and this

**point P is called the point of**

intersection of the given lines.

intersection of the given lines.

**Parallel Lines
Two lines are said to be parallel if they are in the same plane and
do not intersect each other.**

**Perpendicular Lines
Two lines are said to be perpendicular when they intersect at
90 degree (right angle).**

**Example: Use the figure to name:
a) Five points
b) A line
c) Four rays
d) Five line segments**

**a) Five points are O, B, C, D and E.**

b) A line:

c) Four rays are , . and

d) Five line segments are

b) A line:

c) Four rays are , . and

d) Five line segments are

**, , , , ,**

**Example: Use the figure to name:
a) Line containing point E.
b) Line passing through A.
c) Line on which O lies**

**d) Two pairs of intersecting lines.**

a) Line containing point E is

b) Line containing point A is

c) Line on which O lies

d) Two pairs of intersecting lines are and

a) Line containing point E is

b) Line containing point A is

c) Line on which O lies

d) Two pairs of intersecting lines are and

**,**

**and**

**Example: How many lines can pass through
a) One given point?
b) Two given points?**

**a) Infinite number of lines can pass through a given point.**

b) Only one line can pass through two given points.

**Example: Consider the following figure of line MN. Say whether
following statements are true or false in context of the given figure.
(a) Q, M, O, N, P are points on the line **

**(b) M, O, N are points on a line segment .
(c) M and N are end points of line segment **

**.**

(d) O and N are end points of line segment .

(e) M is one of the end points of line segment .

(f) M is a point on ray .

(g) Ray

(d) O and N are end points of line segment .

(e) M is one of the end points of line segment .

(f) M is a point on ray .

(g) Ray

****

**is different from ray .**

(h) Ray

(h) Ray

****

**is same as ray**

**.**

(i) Ray

(i) Ray

**is not opposite to ray**

****

**.**

(j) O is not an initial point of

(j) O is not an initial point of

****

**.**

(k) N is the initial point of and .

(k) N is the initial point of and .

**a) True, points Q, M, O, N, P are points on the line MN. A line**

passing through two points when extends indefinitely can contain

infinite number of points.

b) True, M, O, N are points on the line segment

passing through two points when extends indefinitely can contain

infinite number of points.

b) True, M, O, N are points on the line segment

**.**

c) True, M and N are end points of line segment

c) True, M and N are end points of line segment

**.**

d) False, end points of line segment are O and P.

e) False, end points of line segment are Q and O and not M.

f) False, point M is not on ray .

g) True, the end points of ray

d) False, end points of line segment are O and P.

e) False, end points of line segment are Q and O and not M.

f) False, point M is not on ray .

g) True, the end points of ray

**are O and P whereas the**

endpoints of ray are O and Q in the opposite direction.

Therefore the two rays

endpoints of ray are O and Q in the opposite direction.

Therefore the two rays

**and are different.**

h) False, the end points of ray

h) False, the end points of ray

**are O and P whereas the**

endpoints of ray are O and M in the opposite direction.

Therefore the two rays

endpoints of ray are O and M in the opposite direction.

Therefore the two rays

**and are different.**

i) False, ray is opposite to ray

i) False, ray is opposite to ray

**.**

j) False, O is the initial point of ray

j) False, O is the initial point of ray

**.**

k) True, N is the initial point of and .

k) True, N is the initial point of and .