1. Lesson 2.3 Reflections

2. Warm-Up #

3. Homework

4. Rules of Reflections Reflection x-axis y-axis y = x Find coordinates
Pre-image to image
(x, y)  (x,-y)
(x, y)  (-x, y)
(x, y)  (x, y)
Find coordinates
Multiply y coordinate by -1
Multiply x coordinate by -1
Interchange x and y coordinates

5. Reflects the figure over the y-axis
Use the given rule to transform the figure. Then describe the transformation.
Rule: (x, y)  (-x, y)
0pposite of x’s
Preimage
Image
(1,3)
(-1,3)
(1,1)
(-1,1)
Reflects the figure over the y-axis
(4,1)
(-4,1)

6. Reflects the figure over the x-axis
Use the given rule to transform the figure. Then describe the transformation.
Rule: (x, y)  (x, -y)
0pposite of y’s
Preimage
Image
(1,5)
(1,-5)
(1,3)
(1,-3)
Reflects the figure over the x-axis
(4,3)
(4,-3)

7. Use the given rule to transform the figure
Use the given rule to transform the figure. Then describe the transformation.
Rule: (x, y)  (y, x)
Switch spot
Preimage
Image
(4,5)
(5,4)
(2,1)
(1,2)
Reflect over y = x
(4,1)
(1,4)

8. Reflections across specific lines:
To reflect a figure across the line y = a or x = a, mark the corresponding points equidistant from the line. i.e. If a point is 2 units above the line its corresponding image point must be 2 points below the line.
Example:
Reflect the fig. across the line y = 1.
(2, 3)  (2, -1).
(-3, 6)  (-3, -4)
(-6, 2)  (-6, 0)
Lesson 10-5: Transformations