The document provides an introductory overview of basic geometric concepts including points, lines, and planes, explaining their definitions and representations. It describes the properties of collinear and coplanar points, along with examples to illustrate these concepts. Additionally, it covers intersections of lines and planes, detailing how to visualize and sketch these relationships.

2. Prepared by:
DAIZY ALARCON AVILA
BSED-MATH

3. Objectives:
 describe the undefined terms;
 name the identified point(s), line(s) and
plane(s) in a given figure.
 represents point, line and plane using
concrete and pictorial models.

4. Geometry
It is a Greek word Geo means
“earth” and metron means
“measurement”.
- define as the measure of the
earth
Geometry deals with the shapes
that we see around us.

5. Point
• A point is simply a
location that has no
dimension (width,
length, and thickness),
it is usually represented
by a small dot, and
named by a capital
letter.
A
Point A
B
Point B
C
Point C

6. Line
• A line is a set of points and
extends in one dimension. It
has no thickness or width, is
usually represented by a
straight line with two
arrowheads to indicate that
it extends without end in
both directions, and is
named by two points on the
line or a lowercase script
letter.
A
B
l
Line AB or line l

7. Kinds of Lines
Line Segment
-is a part of the line
with two endpoints
and all the points
between them.
Ray
-is a part of the line
with one endpoint
and extends
indefinitely in one
direction

8. Plane
• A plane is a flat surface made up
of points. It extends in two
dimensions, is usually represented
by a shape that looks like a
tabletop or wall, and is named by
a capital script letter or 3 non-
collinear points. You must
imagine that the plane extends
without end, even though the
drawing of a plane appears to
have edges.
Plane ABC or plane
M

9. A few more basic concepts using
these undefined terms . . .
 Collinear points are points that lie on the
same line.
 Coplanar points are points that lie on the
same plane.

10. Example 1:
Name three points that
are collinear
Solution:
D, E and F lie on the
same line, so they
are collinear.
G
D E F
H

11. Example 2
Name four points that
are coplanar.
Solution:
D, E, F, and G lie on
the same plane, so
they are coplanar.
G
D E F
H

12. Example 3:
Name three points that
are not collinear.
Solution:
There are many
correct answers. For
instance, points H, E,
and G do not lie on
the same line.
G
D E F
H

13. Intersections of Lines & Planes
 The intersection of two or more
lines is a POINT.
 The intersection of two or more
planes is a LINE.

14. Example 4:
 How to sketch a line that
intersects a plane in one
point
 Draw a plane and a line.
 Emphasize the point where
they meet.
 Use dashes to indicate
where the line is hidden by
the plane.