Section 9.1 Introduction to Geometry:
Points, Lines, and Planes
pages 458 - 463
Point
•
•
•
•
A point is a location in space.
It has no size.
It is noted with a capital letter.
It is written as “Point A”, “Point B”,…
.
Line
A
B
n
AB, BA,
or n
• A series of points
that extend in
opposite
directions without
end.
• A lowercase
letter can name a
line.
Plane
• A plane is a flat surface
with no thickness.
• It contains many lines
and extends without
end in the direction of
A
all its lines.
• Notated: ABCD or M
• Examples of planes:
--floor, dry erase
board, desktop
B
M
D
C
Line segment
or segment
• A segment is part of
a line.
• It has two endpoints.
• PQ represents the
length of PQ.
• Noted as PQ or QP
Q
P
Ray
R
C
•
•
•
•
A ray is part of a line.
It has exactly one endpoint.
Name its endpoint first.
Symbolic notation: CR
Use the figure to name each of the following:
H
K
• Four points
I
O
J
• Four different segments
• Five other names for KI
• Five different rays
Intersecting, Parallel, and Skew
Lines
• Two lines intersect if they have
exactly one point in common.
• Two lines that lie in the same plane
and do not intersect are parallel.
• The symbol “ll” is used to indicate
parallel lines.
• Segments and rays are parallel if
they lie in parallel lines.
• Skew lines are lines that do not lie
in the same plane.
• Skew lines are not parallel and do
not intersect.
M
N
T
P
Q
R
S
V
•MN intersects NP
•MN ll QR
•MN and RS are
skew
You are looking directly down into a
wooden crate. Name each of the
following
• Four segments that
intersect PT
• Three segments
parallel to PT
• Four segments skew
to PT
Homework
pages 461 - 463
#s 1-24, 45-48
–
–
–
–
draw diagrams AND
write problems and answers, EXCEPT for
word problems and multiple-choice
problems
SHOW ALL WORK!
failure to write problems and/or show work
will result in either receiving partial or no
credit