1. Geometry warm-up Get a strip of paper from the back desk.
Fold it in half, then half again.
Draw a SpongeBob character in the first frame.
Reflect it into the second frame.
Reflect that one into the 3rd frame.
Then,…. guess what?... Yep. Reflect that one into the 4th frame.

2. On a small piece of paper, write your name, then tell me
the effect of a double reflection.
Do not discuss this with anyone.
Turn it in.

3. Let’s grade your homework
Motion in geometry packet.

4. Motion in the Coordinate Plane

5. Last time we talked about 3 rigid transformations.
Translation …..
Slides
Rotation …..
Turns
Reflection …..
Flips

6. Coordinate Geometry Today… Wait for it…..
We’re going to talk about those same rigid transformations in the coordinate plane. This is called ...
Coordinate Geometry
Wait for it…..

7. Whatever transformation occurred:
moved the x-coordinate 2 units to the right (positive)
and the y-coordinate 4 units up (positive).

8. In our Geometry notation, we can write: T(x,y) = (x + 2, y + 4)
(reminder) Whatever transformation occurred:
moved the x-coordinate 2 units to the right (positive)
and the y-coordinate 4 units up (positive).
THIS SAME OPERATION HAPPENS ON EACH POINT. The result is an image that is congruent to the pre-image.
In our Geometry notation, we can write:
T(x,y) = (x + 2, y + 4)
Read, “the transformation of a point (x,y) moved right 2 and up 4”

9. Activities
Volunteers hand out
Graph paper
Straight edges

13. “What you should have learned” (write these down in your notebook)
Translations ADD
the same number (positive or negative) to each of the x-coordinates
and the same number (could be different from the x-axis addend) to each y-coordinate.
The image is congruent to the pre-image

14. You should have learned this, too (write these down in your notebook)
Reflections –
MULTIPLY the x-coordinate by -1 to reflect across the y-axis
MULTIPLY the y-coordinate by -1 to reflect across the x-axis
for a special reflection:
MULTIPLY both coordinates by -1 to end up with a double reflection: across one axis and then the other.
This is also considered a ROTATION of 180°

15. Rotations
MULTIPLY each coordinate by -1 to rotate a figure 180° about the origin.
Since rotations are based on degrees, there is no ‘rule’ regarding operations on a point.

16. Let’s Play
Interactive Transformations in the Coordinate Plane

17. Assignment
16-3 Packet