What Is a Rotation?
A rotation is a type of translation that swivels a point or polygon around a
fixed point, such as the origin. Rotations are done either clockwise or counter-
clockwise and are measured in degrees. Most commonly, figures are rotated
90° or 180°. In the following figure ΔKAY in is rotated counterclockwise
90° to form ΔK'A'Y'. You should notice how the following rule was
observed in this rotation:
When preimage point A(x, y) is rotated 90° counterclockwisearound the
origin, the image point will be A'(-y, x).
K^1 (–7,5)Can you notice what is happening each time a point
is rotated 90° counterclockwise?A^1 (–4,7)Y(2,–2)K(5,7)Y^1 (2,2) A(7,4)K(5,7) K^1 (–7,5)
A(7,4) A^1 (–4,7)
Y(2,–2) Y^1 (2,2)90° counterclockwise501 Geometry Questions