1. Warm-up
1/13/2019
Reflect the object across the y-axis. Translate the object 4 units right and 3 units up.
Rotate the object 270 degrees counter clockwise around the origin. 3.
4. Draw a concave hexagon
5. Draw a regular pentagon
6. Draw an isosceles right triangle

2. Last Night’s Homework:
Homework Check!
Last Night’s Homework:
HW1 page 399 questions 1-31, all
Today’s Objective: Chapter 7.2 page 404
“Students will know both reflections and line of symmetry.”
22.0 Students know the effect of rigid motions on figures in the coordinate plane and space, including rotations, translations, and reflections.

3. Today’s Objective: Chapter 7.2 page 404
“Students will know both reflections and line of symmetry.”
In a reflection, a line acts like a mirror. The mirror line is called the line of reflection.
Optimus Prime says…
Sha-blam!
Line of Reflection

4. Today’s Objective: Chapter 7.2 page 404
“Students will know both reflections and line of symmetry.”
Bumble Bee says…
While points are easy to
reflect, lines can be more
tricky! Here, a horizontal
line is being reflected.
Sha-blam!
Line of Reflection

5. Today’s Objective: Chapter 7.2 page 404
“Students will know both reflections and line of symmetry.”
Starscream says…
Sloped lines are even
more difficult to reflect.
Here, a sloped line is
being reflected!
Sha-blam!
Line of Reflection

6. Properties of Reflections
Reflections in the coordinate axes have the following properties:
If (x, y) is reflected in the x-axis, its image is the point (x, -y).
If (x, y) is reflected in the y-axis, its image is the point (-x, y).

7. Today’s Objective: Chapter 7.2 page 404
“Students will know both reflections and line of symmetry.”
Sha-blam!
Line of Reflection

8. Theorem 7.1 Reflection Theorem
A reflection is an isometry

9. Today’s Objective: Chapter 7.2 page 404
“Students will know both reflections and line of symmetry.”
Jazz says…
Examples:
A figure in a plane has a
Line of Symmetry if the
figure can be mapped onto
itself by a line of reflection.
Non Examples:

10. Reflections and Line Symmetry
Example: Hexagons can have different lines of
symmetry depending on their shape.
This hexagon has how many lines of symetry?

11. Reflections and Line Symmetry
Given: A Regular Hexagon
This hexagon has six lines of symmetry.

12. Checking For Understanding
Sha-blam!
Let’s start out easy!
Reflect the following points across the line of reflection!
Line of Reflection

13. Checking For Understanding
Line of Reflection
Now try to reflect this line across the line of reflection!
Sha-blam!

14. Checking For Understanding
Line of Reflection
Last one! Reflect the
Rectangle across the line of reflection!
Sha-blam!

15. Checking For Understanding3
How many lines of symmetry does each shape have? 2 2 1 5

16. Checking For Understanding
Define:
Line of Reflection
Isometry
Line of Symmetry
Counter Clockwise
Pre-image
Translation
Mirror line in a reflection transformation.
Transformation in which pre-image and image are congruent.
Line across which a figure can be mapped
onto itself.
To spin to the left.
Starting object.
To glide.
Homework!
HW: page 407 questions 1-29