Math 8: Rigid Transformations
Section #3: Translations. CCSS-8.G. A. 1 & 2.
Corresponds with Module 2, Lessons 4.
Notes #____
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Reflections
Reflection: a transformation that _________________ a figure over a line of reflection so the figure
appears _______________________.
 Reflections are a ____________________________.
Remember, Rigid Transformations preserve the following properties of a figure and its image:
a. _______________________ are mapped to line segments of the same length.
b. __________________ are mapped to angles of the same measure.
c. ________________________________ are mapped to parallel lines.
Reflection over the Y-Axis: The vertices
of ABC are A(1, 6), B(4, 3), and C(2, -1).
Find the image of ABC when it is reflected
over the y-axis.
Reflection over the X-Axis: The line
segment AB has end points A(1, -1) and
(6,3). Find the image line segment AB
when it is reflected over the x-axis.
How to REFLECT a shape:
1. From each _________________, travel to the line of reflection in a __________________ path.
 Perpendicular lines cross at a __________ angle.
2. Determine the __________________ from each vertex to the ____________________________, and
repeat that distance on the _______________ side of the line of reflection.
3. ___________________ each point of the image with _______________.
You Try:
1. a) Graph the image trapezoid ABC after a reflection
in the x-axis.
b) Find the image triangle LMN after a reflection in
the y-axis.
c) If ̅̅̅̅
𝐴𝐵 is 4cm, what is the length of its image? Explain.
d) If <MLN = 30˚, what is the measure of its image? Explain.
̅̅̅̅ and 𝐵𝐴
̅̅̅̅ and their image? Explain
e) What do you know about 𝐶𝐷
Reflections over a GIVEN Line
Reflect C over the line x = 2, then reflect the
image of C over the line y = -1.
You Try:
Graph and label the lines
x = -6 and y = 7.
Math 8: Rigid Transformations
Section #3: Translations. CCSS-8.G. A. 1 & 2.
Corresponds with Module 2, Lessons 4.
HW #____
_________________________________
Reflections
1. a) On the grid, draw the image of trapezoid
MNOP after a reflection over the y-axis and
Label the image M’N’O’P’.
b) On the grid, draw the image of trapezoid
M’N’O’P’ after a reflection over the x-axis and
Label the image M”N”O”P”.
2) The coordinates of ABC are A(0, 5),
B(5, 6), and C(-3, 8). Graph the triangle
and its image after a reflection over the
line y = 1.
MORE ONBACK!!
̅̅ are S(0, 3) and
3) The endpoints of ̅̅
𝑆𝑇
T(5, 5). Graph the line and its image
after a reflection over the line x = 3.
4) Jill reflected the point A(2, 1) over an axis and found the image to be A’(-2, 1). Which axis did Jill
reflect point A over? Explain your reasoning.
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5-8, identify the following transformations as either a translation or reflection.
5) ______________________
6) ______________________
7) ______________________
8) ______________________
H.O.T. Problems (Higher Order Thinking)
Triangle JKL has vertices J(-7, 4), K(7, 1), and L(2, -2). Without graphing, find the coordinates of
vertices of the triangle after a reflection first over the x-axis and then over the y-axis.