1. Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes

2. Warm Up
What geometry term might you associate with each object?
1. one edge of a cardboard box
2. the floor
3. the tip of a pen
line segment or line
plane or rectangle
point

3. Problem of the Day
Remove 4 of the segments to leave 5 equal squares.

4. Learn to identify and describe geometric figures.

5. Vocabulary
point
line
plane
ray
line segment
congruent

6. l XY, or YX, or l X Y A point is an exact
location. It is usually represented as a dot, but it has no size at all.
• A
point A
Use a capital
letter to name
a point. l
A line is a straight path that extends without end in opposite directions.
XY, or YX, or l
Use two points
on the line or a
lowercase letter to
name a line. X Y
A number line is an example of a line.
Helpful Hint

7. Has no thickness and extends forever. plane QRS Use three points
A plane is a
Flat surface that
Has no thickness and extends forever.
plane QRS
Use three points
in any order, not
on the same line,
to name a plane. Q R S
A coordinate plane is an example of a plane.
Helpful Hint

8. Additional Example 1: Identifying Points, Lines, and Planes
Identify the figures in the diagram. D E F
A. three points
D, E, and F
Choose any two points on a line to name the line.
B. two lines
DE, DF
Choose any three points, not on the same line, in any order.
C. a plane
plane DEF

9. Identify the figures in the diagram.
Check It Out: Example 1
Identify the figures in the diagram. G H I F
A. four points
H, G, I, and F
Choose any two points on a line to name the line.
B. two lines
IH, HF
Choose any three points, not on the same line, in any order.
C. a plane
plane IGF

10. A ray is a part of a line.
It has one endpoint and
extends forever
one direction. GH
Name the endpoint
first when naming
a ray. H G
A line segment is
part of a line. or a ray
that extends from one
endpoint to another.
LM, or ML
Use the endpoints
to name a line
segment. L M

11. Additional Example 2: Identifying Line Segments and Rays
Identify the figures in the diagram. M N O
A. three rays
Name the endpoint of a ray first.
MN, NM, MO
B. two line segments
Use the endpoints in any order to name a segment.
MN, MO

12. Check It Out: Example 2
Identify the figures in the diagram. D C
A. three rays
Name the endpoint of
a ray first. B A
BC, CA, BD
B. three line segments
BA, CA, BD
Use the endpoints in any order to name a segment.

13. Figures are congruent if they have the same shape and size
Figures are congruent if they have the same shape and size. Line segments are congruent if they have the same length.
You can use tick marks to indicate congruent line
segments. In the triangle below, line segments AB and BC are congruent.

14. Additional Example 3: Identifying Congruent Line Segments
Identify the line segments that are congruent in the figure.
AB CD
One tick mark
AC BD
Two tick marks
BF DF EC AE
Three tick marks
The symbol means “is congruent to.”
Reading Math

15. Identify the line segments that are congruent in the figure.
Check It Out: Example 3
Identify the line segments that are congruent in the figure. A B C D E
AB AC
One tick mark
BC DE
Two tick marks
BD CE
Three tick marks

16. Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems

17. Lesson Quiz
Identify the figures in the diagram.
1. lines
AD, BE, CF
2. plane
Possible answer: plane ABG
3. three rays
Possible answer: GA, GB, GC
4. four line segments
Possible answer: AG, AD, DG, BG
5. Identify the line segments that are congruent in the figure.
AG GD, GB GE

18. Lesson Quiz for Student Response Systems
1. Identify the lines in the diagram. A.
B. AB, AE C. D.

19. Lesson Quiz for Student Response Systems
2. Identify a plane in the diagram.
A. plane AFD
B. plane EFC
C. plane ABC
D. plane BGF

20. Lesson Quiz for Student Response Systems
3. Identify three rays in the diagram. A. B. C. D.

21. Lesson Quiz for Student Response Systems
4. Identify the line segments that are congruent in the figure. A. B. C. D.