Points, Line and Planes

2. Undefined
Terms in
Geometry

3. Undefined Terms
Words that do not require
formal definition.
In Geometry, there are
three undefined terms.

4. Undefined Terms
Point
Line
Plane

5. Point
A point has no dimension
or actual size.
Thus, it has no length, no
width and no height
(thickness).

6. Point
A point is usually named
with a capital letter.
A
B C
D

7. Point
We can associate point to
our real-life.
Example:
Stars at night Point of a pen

8. Line
A line has infinite length,
no width and no height
and it extends to one
dimension only.

9. Line
A line is named by a single
lowercase script letter, or by
any two (or more) points
which lie on the line.
l
A B
AB

10. Line
Line can also be exhibited to
real-life situation.
Example:
Body of a pencil Curtain Rod

11. Plane
A plane has two dimension
and it extends indefinitely in
all directions. It has infinite
length, infinite width and zero
height.

12. Plane
A plane is named by a single
letter (plane m) or by three
coplanar points, but not non-
collinear point.
m
x
y z
Plane m
Plane XYZ

13. Plane
We can also identify plane to
real-life object.
Example:
Top of a table Book Cover

14. assignment
In a one whole sheet of a yellow
paper, draw three real –life
objects which exhibit the three
undefined terms in Geometry.

15. END