# CLASS-4GEOMETRY - INTRODUCTION

GEOMETRY -

Geometry is very essential part of mathematics. This is also very obvious part of higher mathematics. Three building blocks of geometry are (1) points, (2) lines, and (3) planes.

(1) Point : -

Point is nothing but a dot on a sheet board or paper.

.

Point

Features Of Point -

-  A point is an exact location in space.

-  It has no length and width.

-  It is named by a capital letter.

-  We represent a point by a dot (.)

(2) Straight Line -

--------------------------------

A                                            B

Features Of Straight Line -

-  A line has no breadth, thickness and end points. It cannot be measured.

-  It can be extended to any length on both sides.

-  In symbols line AB is written as

<=>

AB   or    BA

Lines Are Two Types -

Types Of Straight Line -

(A) Parallel Line -

Features Of Parallel Lines :-

The lines that do not meet at any point no matter in whatever direction we continue, are known as parallel lines.

The distance between the parallel lines is always equal.

(B) Intersecting Lines -

Features Of Intersecting Lines :-

The lines or line segments which cross each other at any point are known as intersecting lines.

Non-parallel lines are always intersecting lines.

(C) Perpendicular Lines -

Features Of Perpendicular Lines :-

If two lines intersect each other at right angles, they are called perpendicular lines.

(3Line Segment -

Features Of Line Segment -

-  A portion of a line is called a line segment.

-  A line segment has two end points.

-  It has length and so it can be measured.

-  In symbols line segment AB is written as

__

AB

(4) Ray -

Features Of Ray -

-  A ray is a straight path that goes on and on

in one direction.

-  It has one end point.

Example: The rays of light from a torch.