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Section 3.3 2011.notebook November 18, 2011
Rotation is a transformation in which the points in a plane are moved either clockwise or counterclockwise by an angle with respect to a center point.
Rotation
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Teacher's Notes 2
Teacher's Notes 1
Section 3.3 2011.notebook November 18, 2011
Rotation by 90ο
The coordinates of the image of a point P(x, y) rotated by an angle 90ο counterclockwise will be P'(–y, x)
PointCoordinates
Original ImageABCDE
A
B
C D
E
Solution
Check Your Understanding
Select the correct answer.
1 What are the coordinates of the point P(2, –3) when rotated counterclockwise at an angle 90° around the origin?
A P'(–3, 2)
B P'(–2, –3)
C P'(2, 3)
D P'(3, 2)
Section 3.3 2011.notebook November 18, 2011
Rotation by 180ο
The coordinates of the image of a point P(x, y) rotated by an angle 90οcounterclockwise will be P'(–x, –y)
PointCoordinates
Original ImageABCDE
A
B
C
D
E
Solution
Activity
In the next screen we will perform an activity on matching the coordinates of a point when rotated by a specified angle counterclockwise with the origin as the center of rotation. Drag the coordinates against the correct rotation specification.
Section 3.3 2011.notebook November 18, 2011
Check Your Understanding
Select the correct answer.
2 What are the coordinates of the point P(3, –2) when rotated counterclockwise at an angle 90° around the origin?
A P'(–3, 2)
B P'(3, –2)
C P'(2, 3)
D P'(–2, –3)
Section 3.3 2011.notebook November 18, 2011
Check Your Understanding
Select the correct answer.
3 What are the coordinates of the point P(–4, 1) when rotated counterclockwise at an angle 180° around the origin?
A P'(–4, 1)
B P'(4, –1)
C P'(4, 1)
D P'(–4, –1)
Check Your Understanding
Select the correct answer.
4 A point P(2, 3) is rotated counterclockwise at an angle 90°. What is the quadrant in which the image falls?
A Quadrant I
B Quadrant II
C Quadrant III
D Quadrant IV