Section 1 – 1
Identify Points,
Lines, and Planes
Definition:
Facts/Characteristics:
Has no dimension
and is represented
by a dot.
Examples:
Name a point on the
line
Points A, B or C
●A
Point
point A
Non-examples:
Definition:
Facts/Characteristics:
Has one dimension
and is represented
with two arrowheads
and extends
without end.
Written like this:
Line l, line AB,
line BA
Line
Examples:
Write the line 3 ways
m
D
E
Line m, line DE,
line ED
Non-examples:
Definition:
Facts/Characteristics:
Has two dimensions and
is represented by a shape
that looks like a floor or Plane F, or Plane
a wall and extends
ABC
without end.
Plane
Examples:
Two other names for
plane l
Plane ABC
Plane CAD etc.
Non-examples:
Definition:
Facts/Characteristics:
Points that lie on the
same line.
Points A, B, and C
are all collinear
Collinear
points
Examples:
Non-examples:
Name two collinear points
Points A & D
Points C & E
are not collinear.
Points A, B, E
Points D, B, C
Definition:
Points that lie on
the same plane
Facts/Characteristics:
Points A, B, and C
are all coplanar
Coplanar
Examples:
points
Name 3 coplanar points
Points G, E, O, B
Points F, A, L, I, C
Non-examples:
Points G and F are not
coplanar
Points O and L are not
coplanar
Definition:
Facts/Characteristics:
Part of a line
defined by two
endpoints.
Examples:
Written as:
AB or BA
Segment
What’s another name
for CD
DC
Non-examples:
Watch your symbols:
CD is not CD
Definition:
Part of a line from
a point in one
direction without
end.
Facts/Characteristics:
Written:
ray AB
Written:
Ray
Examples:
Name rays with
endpoint B
Rays BA, BC
BD, BE
Non-examples:
ray BA
Definition:
Facts/Characteristics:
Two connected rays
going in opposite
directions. Opposite
rays make a line.
Examples:
Opposite
Rays
Name 2 sets of opposite
rays
Rays BC and BD
Rays BA and BE
Rays CA and CB
are opposite
Non-examples:
Definition:
Facts/Characteristics:
Two lines intersect
Location where
at
a
point.
two geometric
Two planes intersect
figures have
in a line.
point(s) in
common.
Intersection
Examples:
Lines DC and AB
intersect at point E
Planes Q and P
intersect at line AB
Non-examples:
Homework
Section 1-1
Page 5 – 6
1 – 6,
8 – 12,
17, 18, 20,
25, 26
Vocabulary
Point: Has no dimension and is represented
by a dot.
●A
point A
Line: Has one dimension and is represented
with two arrowheads and extends without end.
l
A
B
line l, line AB or BA
Plane: Has two dimensions and is represented
by a shape that looks like a floor or a
wall and extends without end.
A
M
C
B
plane M or plane ABC
Collinear Points: Points that lie on the same
line.
Coplanar Points: Points that lie in the same
plane.
Segment: Part of a line defined by two
endpoints.
endpoint
A
endpoint
B
segment AB or BA
Ray: Part of a line from a point in one
direction without end.
endpoint
A
B
Ray AB
endpoint
A
B
Ray BA
Opposite Rays: Two connected rays going
in opposite directions. Opposite rays
make a line.
A C
B
Opposite Rays: CA and CB
Intersection: Location where two geometric
figures have point(s) in common.
Two lines intersect at a point.
Two planes intersect in a line.
Example 1
a) Give two other names for BD.
T
D
A
DB and m.
b) Give another name for plane T.
E
C
B
Plane ABE or ABC
c) Name three points that are
m collinear.
A, B, C
d) Name four points that are
coplanar.
A, B, C, E
Example 2
P
T
Q
R
S
c) Which of the rays from 2b
a) Give another name for PR.
are opposite rays?
RP
b) Name all rays with endpoint Q.
QP and QR
QT and QS
QP, QR, QT, QS