Rotations
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Transcript of Rotations
Rotations Chapter 3 Section 8 Course 3
Transformations
example: earth rotates on its axis
Motion Notation Example Translation Slide T<a, b> T<-1, 2>
Reflection Flip Rline Ry-axis
Rotation Turn rx° r90°
Rotation about a point
A rotation – is a turn oThe number of degrees an
image is rotated is called the angle of rotation.
written as rx°(P) = P’
π π
Rotation in the Coordinate Plane When a figure is rotated
90°, 180° or 270° you can use the following rules.
r90°(x,y) =(-y, x)
r180°(x,y) =(-x, -y)
r270°(x,y) =(y, -x)
Example P(-2, 3)
1. r90°(P) =
2. r180°(P) =
3. r270°(P) =
Example A(1, -2)
1. r90°(A) =
2. r180°(A) =
3. r270°(A) =
Example B(4, 1)
1. r90°(A) =
2. r180°(A) =
3. r270°(A) =
Example ABC has vertices A(1, 1), B(1, 6)
and C(4, 1).
r180°(ABC)
Example LMN has vertices L(0, 0), M(3, -5)
and N(-2, -2).
r90°(LMN)
Example L(-2, 5)
1. r90°(L) =
2. r180°(L) =
3. r270°(L) =
Example M(-1, -3)
1. r90°(M) =
2. r180°(M) =
3. r270°(M) =
Example ABC has vertices A(-2, 1), B(-2, -2)
and C(0, 0).
r270°(ABC)
Rotational Symmetry A figure has rotational symmetry if you can rotated (turn) 180° or less and it exactly matches up with the original figure.
Example:
Does the figure have rotational symmetry, reflectional symmetry or
both. 1. 2.
3. 4.