Points and Line Segment

We will discuss here about points and line segment.

POINT: 

A point is basically a dot (•). It is just a mark and has no length. A point is named by a single capital letter. For example, this point is called point X.

We know when two lines meet we get a point.

When two points on a plane surface are joined, a straight line segment is obtained.

But if two points in a curved surface is joined, a curved line segment is drawn.

When a line segment is extended towards both sides unlimitedly it becomes a line. 

We make arrows on both end sides of a line segment to represent a line. 

Now we may say that a part of the line is known as the line segment. If there is a line l, then AB is a line segment. 

A line segment is named by using the names of its endpoints. Then line segment drawn on the side is called line segment AB or line segment BA.

A line does not have any fixed length it has infinite length. But a line segment has a fixed length. We may imagine a line as it has unlimited length but a line segment is drawn on a plane paper.

The core of a cuboid or cube is an example of a line segment. 

Definition of Line Segment:

When two points are joined, the shortest distance between them is called the line segment between those two points.

For example, let us join points X and Y. We can join them in many ways as shown by lines 1, 2 and 3 in the figure given below.

Lines 1 and 3 are curved lines, and line 2 is a straight line.

Can all the three lines be called line segments?

No. Out of lines 1, 2 and 3, line 2 is the shortest.

So, line 2 is the line segment XY. It is written as \(\overline{XY}\).

Note: You can take a thread and actually measure the lengths of lines 1, 2 and 3.

We can say that when two points are joined by a straight line, a line segment is formed.

Hence, a line segment has a starting and an end point.

There are many line segments in the following figures:

Note: Line segments may be joined to form geometric figures.

What is one dimensional figure?

A line or a line segment is called one dimensional (1-D) figure.



Types of lines

There are two types of lines.

(i) Straight line              

(ii) Curved line

Straight Line: If a line shows only one direction, then it is a straight line. It may be vertical, horizontal or slant.

Tom can hear Rita very well over the paper cup telephone. The string between them is held tight and straight

Straight lines can be standing lines, sleeping lines or slanting lines. Join the dots to make straight lines.

Standing Lines	Sleeping Lines	Slanting lines

Join the dots to create your own designs and shapes.

Aaron cannot hear David at all. The string between them is held by loosely in a curve.

Curved lines with open ends	Closed shapes formed by curved lines

Curved line:

It changes its direction.

If you hold the two edges of the string in your hands loosely, it will look like as shown below in the picture.

This is an example of a curved line.

Straight Line

Curved Line

To draw a curved line take a piece of paper. Place a bangle on the paper and draw a line as shown in the picture below. You get a curved line.

Points, lines and line segment are the fundamental concepts in geometry.

Worksheet on Points and Line Segment:

1. Join the number and letter pairs with straight lines and see if you get a curve somewhere.

If you got that right, you should have a design that looks like this:

2. Join the dots using a curved line.

3. Trace over the dotted lines according to the following colour code.

Slanting lines: Blue

Standing lines: Yellow

Sleeping lines: Red

Curved lines: Green

4. Join points A to K. How many points are there?

Answer:

4. 11 points

5. Mark 5 points in the box given below and name them.

● Geometry

• Fundamental Concepts of Geometry
• Points and Line Segment
• Geometrical Shapes
• Two Dimensional Shapes and Lines

2nd Grade Math Practice

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