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TEKS: G1A, G2B, G4B, G6A
The student will develop and awareness of
the structure of mathematical systems.
The student will apply basic facts about
points, lines, segments, rays, and planes.
The student will apply basic facts about lines
and planes.
The most basic figures in
geometry are undefined terms,
which cannot be defined by using
other figures. The undefined
terms point, line, and plane are
the building blocks of geometry.
Building blocks refers to the basic foundation
of geometry.
Vocabulary
Term
Diagram
Name
Point P
P
Point
Line
l
(use capital letters to
name points)
X
Y
Line l
or
XY and YX
Plane
A
C
B
R
plane R
or
plane ABC
Definition
A point names a
location and has
no size. It is
represented by a
dot.
A line is a
straight path
that has no
thickness and
extends forever.
A plane is a flat
surface that has
no thickness
and extends
forever.
Vocabulary
Term
Segment
Diagram
Name
Definition
AB
A
B
or
BA
Endpoint
Ray
C
D
R
S
S
Opposite
Ray
F
An endpoint is a
C and D point at the one
end of a segment
(use capital letters to or starting point
name points)
of a ray
RS
R
E
G
A segment or line
segment is the
part of a line
consisting of two
points and all the
points between.
EF and EG
A ray is a part of a
line that starts at
an endpoint and
extends forever in
one direction.
Opposite rays are
two rays that have
a common
endpoint and form
a line.
Points that lie on the same line are collinear.
K, L, and M are collinear.
K, L, and N are noncollinear.
Points that lie on the same plane are coplanar.
Otherwise they are noncoplanar.
K
L M
N
Draw and label a ray with endpoint F that
passes through G.
A. Name four coplanar points.
A, B, C, D
B. Name four lines.
Possible answer: AE, BE, CE, DE
Refer to the architectural
design of the Central
Library building.
1. Name four coplanar
points.
K, L, M, and N all lie in
plane R.
2. Name three lines.
AB ,BC , and CA
A postulate, or axiom, is a
statement that is accepted as true
without proof. Postulates about
points, lines, and planes help
describe geometric properties.
Teacher Notes: Demonstrate with pencils and note cards.
A. Sketch two lines intersecting in exactly one point.
B. Sketch a figure that shows a line that lies in a
plane.
Sketch a figure that shows two lines intersect in one
point in a plane, but only one of the lines lies in the
plane.
Note: Use a dashed line to show the hidden parts of any figure that you are
drawing. A dashed line will indicate the part of the figure that is not seen.
Sketch a figure that shows a line that intersects two
nonintersecting planes.
Sketch a figure that shows three coplanar lines that
intersect in three different points.