Look around!
You can see lines everywhere!

★ LINES, LINE SEGMENTS, RAYS ★

There are different kinds of lines too!
Let's learn about these basic ideas in Geometry!
1. LINE

A line is a straight path that goes on forever in both directions.

It has no end.
Example

This is a line.

l
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We use arrow heads (  ← →  ) on both ends to show that a line extends forever.
2. LINE SEGMENT

A line segment is a part of a line that has two end points.

A B
It has a definite beginning and end.
Example

This is a line segment.

A B

It is written as AB or BA

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We use a dot (  ●  ) on both ends to show the end points.
3. RAY

A ray is a part of a line that has one end point and goes on forever in one direction.

P
It has a beginning but no end in one direction.
Example

This is a ray.

P Q

It is written as PQ

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We use a dot (  ●  ) at the beginning and an arrow (  →  ) at the other end.
4. TYPES OF LINES

There are different types of lines.

1
Horizontal Line
It is straight and goes from left to right.
2
Vertical Line
It is straight and goes from top to bottom.
3
Slanting (Oblique) Line
It is straight but it is not horizontal or vertical.
4
Parallel Lines
These lines are always the same distance apart and never meet.
5
Intersecting Lines
These lines cross each other at a point.
6
Perpendicular Lines
These lines meet each other at a right angle (90°).
7
Curved Line
It is not straight and bends gently.
5. LET'S SEE IN REAL LIFE!
Line

Roads, strings, railway tracks, electric wires

Line Segment

Edge of a book, ruler, pencil, sticks

Ray

Sun rays, torch light, laser light

6. COMPARE AND REMEMBER
Type Ends How it looks Symbol Example
Line No end
(on both sides)		 l
(small letter)		 AB
Line Segment Two
end points		 AB
(2 capital letters)		 AB
Ray One
end point		 PQ
(2 capital letters)		 PQ
7. QUICK TIPS
  • ★ A line goes on forever in both directions.
  • ★ A line segment has two end points.
  • ★ A ray has one end point and goes on forever in one direction.
  • ★ Look for arrow heads and dots, they help you identify!
8. PRACTICE TIME!

A. Name the type of each.

  1.  ___________
  2.  ___________
  3.  ___________

B. Write the correct symbol.

  1. Line AB  ___________
  2. Line Segment CD  ___________
  3. Ray XY  ___________

C. Draw each.

  1. A line
  2. A line segment
  3. A ray
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Remember: Observe, Identify and Practice to become a Geometry Star!