Rotatio

1. 9.4 Rotations
HW pg. 602 #4­20 evens, except 10
February 06, 2015
Bellwork
4. Find the point C on the x­axis so AC + BC is a
minimum for A(2, 5) and B(7, 3).
(2 ,
5)
(7 ,
­3)
­7 ­6 ­5 ­4 ­3 ­2 ­1 0 1 2 3 4 5 6 7
­7
­6
­5
­4
­3
­2
­1
1
2
3
4
5
6
7
x
y

2. 9.4 Rotations
HW pg. 602 #4­20 evens, except 10
February 06, 2015
9.4 Rotations
Center of Rotation: figure is turned about a fixed point
Angle of Rotation: rays drawn from center of rotation to
a point and its image

3. 9.4 Rotations
HW pg. 602 #4­20 evens, except 10
February 06, 2015
Rules for Rotations about the Origin:
90 : (­y,x)
180 : (­x,­y)
270 : (y,­x)

4. 9.4 Rotations
HW pg. 602 #4­20 evens, except 10
February 06, 2015

5. 9.4 Rotations
HW pg. 602 #4­20 evens, except 10
February 06, 2015
Rotation Matrices
270 : 0 1
­1 0[ [90 : 0 ­1
1 0[ [
180 :
[[­1 0
0 ­1
360 : 1 0
0 1[ [

6. 9.4 Rotations
HW pg. 602 #4­20 evens, except 10
February 06, 2015
Rotation Theorem: A rotation is an isometry.

7. 9.4 Rotations
HW pg. 602 #4­20 evens, except 10
February 06, 2015
HW pg. 602 #4­20 evens