4. GENERAL OBJECTIVES
Pupil will be able to :-
Understand the properties of
quadrilaterals.
Distinguish between different types
of quadrilaterals.
Grasp the concept of symmetry in
different types of quadrilaterals
5. What is geometry ?
Geometry is the branch of
mathematics which deals with
properties and relations with the lines
, angles ,surfaces and solids. Just as
Maths deals with numbers , geometry
deals with figures , points and
lines…….
6. POINT
A point is usually represented by a small dot.
By a sharp tip of the pencil, mark a dot on the
paper. Sharper the tip, thinner will be the dot.
7. Line Segment
A line segment corresponds to the
shortest distance between two points.
The line segment joining points A and B
is denoted by AB
8. This shortest join of
point A to B
(including A and B)
shown here is a line
Segment.
AB
9. Line
A line is obtained when a line segment like
AB is extended on both sides indefinitely; it
is denoted by AB or sometimes by a single
small letter like l.
A
B AB
11. Parallel Lines
Two lines in a plane are said to be parallel if
they do not meet.
Identify parallel lines
12. Ray
A ray is a portion of a line. It starts at one
point (called starting point) and goes endlessly
in a direction.
A
P
Two
points are shown on the ray.
They are (a) A, the starting
point (b) P, a point on the path
of the ray.
We denote it by AP.
13. some models for a ray
Beam of light from
a light house
Ray of light
from a torch
Sun rays
14. POLYGON
A polygon is a simple closed curve made up of line
segments.
(i) The line segments are the sides of the polygon.
(ii) Any two sides with a common end point are adjacent
sides.
(iii) The meeting point of a pair of sides is called a vertex.
(iv) The end points of the same side are adjacent vertices.
(v) The join of any two non-adjacent vertices is a diagonal.
15. Angles
An angle is made up of two rays starting from
a common end point.
Two rays OA and OB make ∠AOB(or also
called ∠BOA).
o
A
B
∠AOB
ANGLE AOB
16. The meeting point of a pair of sides is
called a vertex.
The end points of the same side are
adjacent vertices
17. Triangles
A triangle is a three-sided polygon
The three sides of the
triangle AB , BC and CA .
The three angles are
∠BAC, ∠BCA and ∠ABC.
The points A, B and C are
the vertices of the triangle
18. Quadrilaterals
A four sided polygon is a quadrilateral
It has 4 sides and 4 angles.
Four sides AB, BC , CD and
DA.
Four angles ∠A , ∠B, ∠C
and ∠D
19. AB and DC are opposite sides
∠A and ∠C, ∠D and ∠B are opposite angles
20. Circles
A circle is a simple closed curve which is not a
polygon.
Parts of circle
1.Centre - The fixed point
2.Radius- fixed distance
3.Diameter -A diameter is a chord passing through the
center
4.Chord-line segment joining any two points on the
circle.
5.Circumference – distance around the circle.
21. The fixed point is the center
The fixed distance is the radius
A diameter is a chord passing through the center of the circle.
A chord of a circle is a line segment joining any two points on
the circle.
The distance around the circle is the circumference.
1.Centre - o
2.Radius - r
3.Diameter - d
4.Chord - ca
5.cirumference
o
r
d
c
a
22. A region in the interior of a
circle enclosed by an arc on
one side and a pair of radii on
the other two sides is
called a sector.
A region in the interior of a
circle enclosed by a chord and
an arc is called a segment of
the circle.
23. Learning outcome
Students will be able to
Understand the concept of point ,
line , line segment , ray ,angle ,
triangle , quadrilateral and circle.
Apply the knowledge in different
situations.
