CLASS VI

What is Geometry????!!!??

Geometry is the branch of mathematics which deals with the properties and relations of lines , angles , surfaces and solids. Just as maths deals with numbers, geometry deals with figures , points and lines…..

A point is usually represented by a small dot and is name by a single capital letter of alphabet<see fig.1>.It has no magnitude i.e. has no length, breadth or thickness.

Fig.1

A line is straight and extends indefinitely on both sides<see fig.1>.

Fig.1

Line-

Line segment-A part of a line is called a line segment.<see fig.2>.

Fig.2A B

A ray is a part of a line, which has one end point, and extends indefinitely on the other side<see fig.1>

A

A plane is a flat surface that extends indefinitely in all directions. The surface of the wall is an example of a plane.<see fig.1>.

Fig.1

An angle is formed by two rays starting from the same initial point. The initial point O is called the vertex. Rays OA and OB are called the arms of the angle.

O

A

B

A

CB

A triangle is a three sided closed figure, formed by three line segments intersect in pairs. A,B and C are known as the vertices (singular vertices) of the triangle. A triangle has:-

1.Three sides AB,BC and CA.

2.Three angles <A,<B and <C.

3.Three vertices A, B & C

INTERIOR

EXTERIOR

NO

D

ALTITUDE

A quadrilateral is a four sided figure. ’ Quadri ’ means four, and ‘ lateral ‘ means sides. If A,B,C and D are four points in a plane such that no three of them are collinear and the line segments AB,BC,CD and DA do not intersect except at their end-points, then the figure formed by these four line segments is called the quadrilateral ABCD.

A D

B C

ADJACENT SIDES

BC & AD are opposite sides.

. o

A circles a set of points on a plane which are at the same distance from a fixed point called centre (O).B A

OB=RADIUSAB=DIAMETER< 2 X RADIUS >

INTERIOR

EXTERIOR

CHORDC D

E

CED is the minor arc and CSD is The major arc.

S

LEARNING OUTCOMES

Students will be able to

*understand the concept of a point, line, line-segment, ray, plane, angle, triangle, quadrilateral, circle.

*apply the knowledge in different situations.