Details matter when naming
things in Geometry!
You must consider how the symbol is written:
 Capital letters / lowercase
 Print / cursive
 How many letters used
 Order of letters
 With an extra symbol or without
 Some things have more than one way to name them
Name
Point
Symbols Like…
One CAPITAL
print letter:
A
Simple Definition
A dot; a location on a
graph
Picture
Name
Line
Symbols
(2 methods!)
Simple
Definition
two capital letters with
double arrow on top:
A string of
points that
AB
line up and
continue
single lowercase
forever in
cursive letter
both
with nothing else:
directions
Picture
Name
line
segment
Symbols
the two
endpoints are
CAPITALIZED
with a bar on
top, in either
order:
AB
or
BA
Simple Definition
Part of a line, has two
endpoints
Picture
A
B
Name
Symbols
Simple Definition
Half of a line, has one
endpoint
ray
AB
Must be
written
first
Picture
Name
angle
Symbols
(3 methods!)
Simple Definition
With a number:
1
With three letters
(vertex in middle):
ABC or CBA
With the vertex only
(unless more than
one angle uses same
vertex): B
Picture
A
Two rays that have a
common endpoint
connecting them
B
C
vertex
Name
plane
Symbols
(2 methods!)
Simple
Definition
Picture
One CAPITAL CURSIVE
letter : M
Any three points in the
plane as long as they
are not on the same
line:
ABC
(order does not matter,
must be CAPITALIZED)
A flat surface
that extends
forever
A
B
C
M
OTHER SYMBOLS
The measure of a segment tells how long it is. It is shown by
removing the bar and just using the two letters: AB
The measure of an angle tells how many degrees it has. It is
shown by putting a small “m” in front of the angle’s name:
mABC
Congruent means two things have the same measure. It looks
like an equal sign with an extra squiggle on top:

Additional Vocabulary:
Collinear points are points that lie on the same line.
Coplanar points are points that lie on the same plane.
- Share a common starting point and go in
opposite directions to form a line
intersection – where things meet or cross
Now work on
SYMBOL PRACTICE # 1
Geometry Symbols Practice # 1
Tell if each is a point, line, plane, line segment, ray, angle, measure of a line
segment, measure of an angle, or "nothing". (Answers next page.)
1. location in space; no actual size
2. part of a line between two endpoints
3. "half of a line" extending in one direction forever
4. an infinite string of points; has no actual thickness
5. flat surface that extends indefinitely in all directions; no
actual thickness
Geometry Symbols Practice # 1
Tell if each is a point, line, plane, line segment, ray, angle, measure of a line
segment, measure of an angle, or "nothing".
1. location in space; no actual size point
2. part of a line between two endpoints line segment
3. "half of a line" extending in one direction forever ray
4. an infinite string of points; has no actual thickness line
5. flat surface that extends indefinitely in all directions; no
actual thickness plane
Tell if each is a point, line, plane, line segment, ray, angle, measure of a line
segment, measure of an angle, or "nothing". (Answers next page.)
6. one CAPITAL letter
cursive letter
8. single UPPERCASE Cursive letter
7. single lower-case,
9. two CAPITAL letters with → on top
10. three CAPITAL letters with no other symbol
11. two printed CAPITAL letters with ↔ on top
12. two CAPITAL letters with a — on top
Tell if each is a point, line, plane, line segment, ray, angle, measure of a line
segment, measure of an angle, or "nothing".
6. one CAPITAL letter
point
cursive letter line
8. single UPPERCASE Cursive letter plane
7. single lower-case,
9. two CAPITAL letters with → on top
ray
10. three CAPITAL letters with no other symbol
plane
11. two printed CAPITAL letters with ↔ on top line
12. two CAPITAL letters with a — on top
segment
Tell if each is a point, line, plane, line segment, ray, angle, measure of a line
segment, measure of an angle, or "nothing". (Answers next page.)
Tell if each is a point, line, plane, line segment, ray, angle, measure of a line
segment, measure of an angle, or "nothing".
plane
line
point
angle
ray
segment
Measure of
an angle
angle
Tell if each is a point, line, plane, line segment, ray, angle, measure of a line
segment, measure of an angle, or "nothing". (Answers next page.)
Tell if each is a point, line, plane, line segment, ray, angle, measure of a line
segment, measure of an angle, or "nothing".
plane
segment
line
ray
line
point
NOTHING
plane
Arrow wrong way
Measure of a
segment
Measure
of an angle
line
segment
angle
NOTHING
No bar over planes
angle
Measure of an
angle
NOTHING
Planes capitalized
NOTHING
With arrow, lines
must be capitalized;
if cursive, use one
small letter and no
arrow
Answers next page.
Answers next page.
It must be the vertex.
It must be the endpoint. It should not be from the side with the arrow.