This document defines and explains various geometrical terms related to lines, angles, and their relationships. It begins by defining a point, line, line segment, and ray. It then explains different types of angles like acute, obtuse, right, and congruent angles. It also describes relationships between angles like adjacent angles, vertically opposite angles, complementary angles, supplementary angles, and linear pairs of angles. Diagrams are provided with each term to illustrate the definitions and relationships.

1. WELCOME
ST. Peter’s College
of Education
Presented by,
FARZANA BEGUM
Roll No. 17

2. Line
s &Angle
s

3. Point
An exact location on a plane is
called a point.
Line
Line
segment
Ray
A straight path on a plane,
extending in both directions
with no endpoints, is called a
line.
A part of a line that has two
endpoints and thus has a
definite length is called a line
segment.
A line segment extended
indefinitely in one direction
is called a ray.
Recap Geometrical Terms

5. RAY: A part of a line, with one endpoint, that continues
without end in one direction
LINE: A straight path extending in both directions with no
endpoints
LINE SEGMENT: A part of a line that includes two
points, called endpoints, and all the points between
them

6. INTERSECTING LINES: Lines that cross
PARALLEL LINES: Lines that never cross and are always
the same distance apart

7. Common
endpoint
B C
B
A
Ray BC
Ray BA
Ray BA and BC are two non-collinear rays
When two non-collinear rays join with a common endpoint
(origin) an angle is formed.
What Is An Angle ?
Common endpoint is called the vertex of the angle. B is the
vertex of ABC.
Ray BA and ray BC are called the arms of ABC.

8. To name an angle, we name any point on one ray, then the
vertex, and then any point on the other ray.
For example: ABC or CBA
We may also name this angle only by the single letter of the
vertex, for example B.
A
B
C
Naming An Angle

9. An angle divides the points on the plane into three regions:
A
B
C
F
R
P
T
X
Interior And Exterior Of An Angle
• Points lying on the angle
(An angle)
• Points within the angle
(Its interior portion. )
• Points outside the angle
(Its exterior portion. )

10. Right Angle:
An angle that forms a
square corner
Acute Angle:
An angle less
than a right angle
Obtuse Angle:
An angle greater
than a right angle

11. Two angles that have the same measure are called congruent
angles.
Congruent angles have the same size and shape.
A
B
C
300
D
E
F
300
D
E
F
300
Congruent Angles

12. Pairs Of Angles : Types
• Adjacent angles
• Vertically opposite angles
• Complimentary angles
• Supplementary angles
• Linear pairs of angles

13. Adjacent Angles
Two angles that have a common vertex and a common ray
are called adjacent angles.
C
D
B
A
Common ray
Common vertex
Adjacent Angles ABD and DBC
Adjacent angles do not overlap each other.
D
E
F
A
B
C
ABC and DEF are not adjacent angles

14. Vertically Opposite Angles
Vertically opposite angles are pairs of angles formed by two
lines intersecting at a point.
APC = BPD
APB = CPD
A
DB
C
P
Four angles are formed at the point of intersection.
Point of intersection ‘P’ is the common vertex of the four
angles.
Vertically opposite angles are congruent.

15. If the sum of two angles is 900, then they are called
complimentary angles.
600
A
B
C
300
D
E
F
ABC and DEF are complimentary because
600 + 300 = 900
ABC + DEF
Complimentary Angles

16. If the sum of two angles is 1800 then they are called
supplementary angles.
PQR and ABC are supplementary, because
1000 + 800 = 1800
RQ
P
A
B
C
1000
800
PQR + ABC
Supplementary Angles

17. Two adjacent supplementary angles are called linear pair
of angles.
A
600 1200
PC D
600 + 1200 = 1800
APC + APD
Linear Pair Of Angles