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Rotations . Chapter 3 Section 8 Course 3 . Transformations . example: earth rotates on its axis . Rotation about a point . π. A rotation – is a turn The number of degrees an image is rotated is called the angle of rotation. written as r x ° (P) = P’. π.
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Rotations Chapter 3 Section 8 Course 3
Transformations example: earth rotates on its axis
Rotation about a point π A rotation – is a turn • The number of degrees an image is rotated is called the angle of rotation. written as rx°(P) = P’ 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.