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1.1 Building Blocks
of Geometry
Identifying lines, rays, and
segments
VOCABULARY
Point – usually labeled with an uppercase letter.
Describes a specific location in space.
Line – points that extend without end in two opposite
directions
Read as: “line NO or line ON”
N
O
Symbol: NO or ON
Ray – has one endpoint and extends without end in one
direction. Always when naming give the endpoint first.
B
A
Read as: “ray AB”
Symbol: AB
Identifying lines, rays, and
segments continued….
Segment – a piece of a line which
has two endpoints
●
●
B
E
Read as: “line segment BE or
line segment EB”
Symbol:
BE or EB
NOTE: You may have the points
at the end of the segment or
without.
Plane – flat surface that extends indefinitely along its
length and width
Read as: plane ABC
Identifying lines, rays, and
segments continued….
Parallel lines – two different lines
that will never intersect no matter how
far they extend.
C
D
“Line CD is parallel to
line YZ.”
Y
CD | | YZ
Z
Intersecting lines – two different lines that meet at a point
Q
T
S
P
“Line TS intersects
with line PQ”
Let’s Do Some Examples!
Identify and name the line, ray, or segment.
S
M
1.
N
ray
MN
or
2.
Q
●
3.
R
line segment
NM
P
●
QP or PQ
line
RS or
SR
Now You Try!
Identify and name the line, ray, or segment.
G
ray
GF or
FG
F
line
H
●
K
HJ or
JH
J
L
●
segment
KL or
LK
Now You Try Continued
G
H
J
K
L
1. Name 2 rays.
HL or GK or JL or JK
2. Name 2 segments that have
G as an endpoint.
3. Name a line.
GH
4. Name 3 points.
GH and GJ
Any 3 that includes L or J or K or H or G
Now You Try Continued
A
B
C
D
G
F
E
1. Name a pair of intersecting lines.
2. Name a pair of parallel lines.
3. Name DB and BA another way.
AB and EG or CF and EG
AB and CF
BD and AB
Midpoint
Midpoint – The midpoint of a segment is the point on
the segment that is the same distance from both
endpoints.
Bisects – The midpoint bisects the segment,
meaning that it divides it into two congruent segments
M is the midpoint of AB.
1.2 Angles
What is an angle?
Angle – An angle is formed by two rays that share a
common endpoint
Vertex – The common endpoint of the two rays
Sides – The two rays
Point B is the vertex of angle ABC.
The angle may also be referred to
as angle CBA, angle B,
, or
Angle measures
Angle measures – can be
anywhere between 0 and 180
degrees.
“The measure of angle A is 45
degrees”
Using a protractor
1) Place hole in center of protractor on vertex
2) Align first ray along line on bottom of protractor
3) Use other ray to find angle measure