Day4 Reflections Lesson CHS- Geometry
There are 4 major types of Transformations
There are 4 major types of transformations
Rotations
There are 4 major types of transformations
Rotations
Reflections
There are 4 major types of transformations
Rotations
Reflections
Translations
There are 4 major types of transformations
Rotations
Reflections
Translations
Dilations
How many major types of transformations are there?
Today we will learn about Reflections
A reflection flips the point over a line
Translation
Reflection
Shifts
?
Flips
?
A reflection flips the point over a line
A reflection flips the point over a line
A y axis reflection
A reflection flips the point over a line
A y axis reflection
would flip the point
over the y axis
A reflection flips the point over a line
A y axis reflection
would flip the point
over the y axis
A reflection flips the point over a line
A y axis reflection
So it is the same distance
would flip the point
on both sides
over the y axis
A reflection flips the point over a line
2
A y axis reflection
So it is the same distance
would flip the point
on both sides
over the y axis
A reflection flips the point over a line
2
A y axis reflection
So it is the same distance
2
would flip the point
on both sides
over the y axis
A reflection flips the point over a line
An x-axis reflection
flips over the x-axis
A reflection flips the point over a line
An x-axis reflection
flips over the x-axis
A reflection flips the point over a line
So that the point is the
An x-axis reflection
same distance from the 
flips over the x-axis
x-axis
A reflection flips the point over a line
3
So that the point is the
An x-axis reflection
same distance from the 
flips over the x-axis
x-axis
A reflection flips the point over a line
3
3
So that the point is the
An x-axis reflection
same distance from the 
flips over the x-axis
x-axis
Which point is point A reflected across the y-axis?
Which point is point A reflected across the x-axis?
A
C
B
A reflection across the x axis also changes the 
sign of the y value
A reflection across the x axis also changes the 
The point (-2, 3) reflected across the x axis would be
sign of the y value
A reflection across the x axis also changes the 
The point (-2, 3) reflected across the x axis would be
sign of the y value
(-2, -3)
A reflection across the x axis also changes the 
The point (-2, 3) reflected across the x axis would be
sign of the y value
(-2, -3)
Notice the sign of the y changes
      Rule:
(x,y) --> (x, -y)
A reflection across the y axis changes the sign of the x
The point (2,-3) reflected across the y axis would be
      Rule:(x,y) --> (-x, y)
A reflection across the y axis changes the sign of the x
The point (2,-3) reflected across the y axis would be
(-2, -3)
      Rule:(x,y) --> (-x, y)
A reflection across the y axis changes the sign of the x
Notice the change in x
The point (2,-3) reflected across the y axis would be
(-2, -3)
      Rule:(x,y) --> (-x, y)
Point (-1,4) reflected across the y axis
Point (-5,3) reflected across the x axis
Point (5,7) reflected across the x axis
(5,
(
(
,4)
,
)
)
A reflection flips the point over a line
Here is the line y = x
A reflection flips the point over a line
Here is the line y = x
A reflection flips the point over a line
Reflections are always 
perpendicular to the 
line of reflection.
Here is the line y = x
A reflection flips the point over a line
Reflections are always 
perpendicular to the 
line of reflection.
Notice how the coordinates 
switch:
The rule for a reflection over 
the line y = x is 
(x,y) --> (y, x)

Here is the line y = x
A reflection flips the point over a line
(-2, 3)
(3, -2)
Point (2,-7) reflected across the line y=x
Point (-8,-12) reflected across the line y=x
Point (-5,3) reflected across the line y=x
(          ,        )
(       ,      )
(
,
)
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