Basic Concepts in Geometry

Introduction

Look around you. The edge of a table, the beam of a torch, railway tracks, and even a dot on a map can help us understand geometry.Geometry is a branch of mathematics that deals with shapes, sizes, positions, and the relationships between different objects. In this chapter, we will learn about the basic concepts of geometry:
1. Point
2. Line Segment
3. Ray
4. Line
5. Parallel Lines
These concepts form the foundation for learning geometry.

Chapter Overview

A geometric figure begins with a point.
A point can form a line segment. A line segment can help us understand rays and lines. When two lines remain the same distance apart and never meet, they are called parallel lines.
Learning Path:
1. Point
2. Line Segment
3. Ray
4. Line
5. Parallel Lines

1. Point

A point shows an exact position or location.
A point has no length, width, or thickness. It only indicates a position.
A point is usually represented by a small dot and named using a capital letter.

2. Line Segment

Suppose we join two points using a straight path. The part of the line between the two points is called a line segment. A line segment has two endpoints and a fixed length.

Has two endpoints.
Has a definite length.
Can be measured using a ruler.

Examples of line segments include:
The edge of a ruler.
A ruler.
A pencil.

3. Ray

A ray is a part of a line that starts from a fixed point and extends endlessly in one direction. The fixed point is called the endpoint. The ray starts at A and continues endlessly in one direction. It is written as Ray AB.

Has one endpoint.
Extends endlessly in one direction.
Cannot be measured completely.

4. Line

A line is a straight path that extends endlessly in both directions. A line has no endpoints. The arrows show that the line continues endlessly in both directions.

Has no endpoint.
Extends endlessly in both directions.
Cannot be measured completely.

Examples that resemble a line are:
A straight road stretching far ahead.
A stretched wire.

4. Parallel Lines

Two lines in the same plane are called parallel lines if they never meet, no matter how far they are extended. The distance between parallel lines remains the same throughout.

Remain the same distance apart.
Never intersect.
Extend endlessly.

Examples that resemble a line are:
Railway tracks
Lines in a notebook

Summary

A geometric figure begins with a point.
In this chapter, we learned about the fundamental concepts of geometry.
1. A point represents an exact position.
2. A line segment joins two points and has a fixed length.
3. A ray begins at one point and extends endlessly in one direction.
4. A line extends endlessly in both directions.
5. Parallel lines remain the same distance apart and never meet.