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Reflections
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by David Kwan
| 10 Questions
Note from the author:
This Formative is by: Brian Gervase

This mini lesson introduces students to the formal definition of a reflection. Students have the opportunity to play with reflections in a guided fashion using Geogebra applets.
In this mini-lesson you will get a chance to play with our 3rd type of transformation -- reflections-- and understand the formal definition of a reflection in geometry.

In the sketch below, click the box that says "Reflection Image" and PLAY with the results. Do not click the show measurements yet. Be sure to move ALL points on the screen and try to get a good physical understanding about how the reflection is generated.
The outlined content above was added from outside of Formative.
1
1 pt
The image of a reflection is congruent to the preimage.
True
False
2
1 pt
Which line above is considered the 'mirror' in this reflection?
AB
BC
CD
EF
3
1 pt
A reflection over a mirror is the same as a 180 degree rotation about a point on the mirror.
True
False
Now click the box in the above sketch that says "Show Measurements". Again play and make some observations about the geometry of the reflection.
4
1 pt
Choose all statements below that are true.
The image and preimage are congruent.
The image COULD be a 180 degree rotation of the preimage.
Line AA' is perpendicular to the mirror.
EF bisects segment DD'.
Segment CC' bisects line EF.
There is a point, Q, on EF such that BQ = B'Q.
5
1 pt
Consider a line on your desk and a point P. Explain how you would find P' , the image of P reflected over the line on your desk. Be specific about what you would have to measure in order to locate P'.

6
1 pt
Use a graph board or Geogebra in another window to visualize and find the indicated point.

Enter the coordinates of P' which is the reflection of P(3,5) over the y-axis.

7
1 pt
Use a graph board or Geogebra in another window to visualize and find the indicated point.

Enter the coordinates of P' which is the reflection of P(3,5) over the x-axis.

8
1 pt
Use a graph board or Geogebra in another window to visualize and find the indicated point.

Enter the coordinates of P' which is the reflection of P(3,5) over the line y = x.

9
1 pt
Use a graph board or Geogebra in another window to visualize and find the indicated point.

Enter the coordinates of P' which is the reflection of P(1,-2) over the line -x + 3y = 3.