1. Bellwork
What is the coordinate rule for the translation that maps A (-7, 2) onto A’ (3, -1)?
What is the image of F(72, - 4) after the following transformations? Use F as the pre-image for each.
T −11, 6 (F)
Reflection across the y-axis
Reflection across the x – axis
Reflection across y = x

2. 9-3: Rotations
Rigor: Students will rotate figures about a point on and off the coordinate plane.
Relevance: Rotations describe movement.

3. Rotations
Turn to page in your core book and highlight bullets 1 - 3:
A rotation turns all points about a point called the center of rotation. (pg 383)
Rotation is always counterclockwise unless otherwise specified (pg 383)
A Rotation is: a rigid transformation, image is the same distance from center as pre-image, all points rotate to image by the same angle of rotation. (pg 384)
Function Notation: r (Q, xo) (pre-image)
center of rotation angle of rotation

4. Rotating Increments of 90o on a Grid
Trace your pre-image and center of rotation on both sides of your tracing paper
Put a + sign over your center of rotation on the tracing paper
Put your pencil on the center of rotation and turn tracing paper until + lines up again. Each time the + maps onto itself you have rotated 90o!
Rotations worksheet (graded classwork)
Things to think about:
Which figures land in the same place? Why?
How does the point of rotation change how far the figure travels?

5. Rotating Off a Grid Workbook page 384 Example 2
Use a protractor to draw the desired angle with the center of rotation as the vertex
Trace the pre-image and the segment connecting the preimage to the center of rotation
Retrace the figure on the other side of the tracing paper
Rotate tracing paper so that the segment lines up with the other side of the angle
Trace figure to imprint image onto your workbook
Additional Practice: workbook pg 386 #1 - 3

6. Special Rotations in the Coordinate Plane Highlight coordinate rules on pg 385, add 360o Rule

7. Examples from the core book
Rotating about the origin: EX 3 pg 385 (Label vertices A, B, C, D)
Pg 386 – 387 #4 - 7

8. Does Prime Notation Really Matter?
What transformation would map ABCD onto each square?

9. Rotations in Regular Polygons
A regular polygon has congruent sides and congruent interior angles.
You can divide any regular polygon into congruent triangles.
When you rotate a regular polygon about its center, the sides will line up when you rotate it a certain number of degrees, called the central angle.

10. Example
Point X is the center of the regular polygon PENTA. What is the image for the given rotations? A) 72o rotation of E about X. B) r (216o, X) ( 𝐸𝑁 )

11. Real Life Example
The London Eye observation wheel takes 30min to make a complete rotation. What is the angle of rotation of a car after 5 minutes? How many minutes would it take for the car to rotate 270o?

12. 9-3 Assignment From the Workbook
Pg 389 #5 – 10 (honors also #11)
Pg 390 #1, 3, 4, 5, 7
Due Tuesday: Periods 2, 4, & 6
Due Wednesday: Periods 1, 5, & 7