The problem asks which of the given rotations about the origin will transform the point $A(-X, y)$ to the point $A'(X, -y)$.

GeometryRotationsCoordinate GeometryTransformations
2025/4/28

1. Problem Description

The problem asks which of the given rotations about the origin will transform the point A(X,y)A(-X, y) to the point A(X,y)A'(X, -y).

2. Solution Steps

We need to determine the rotation that maps (X,y)(-X, y) to (X,y)(X, -y).
Let's analyze each option:
(a) R(O,90)R(O, -90^\circ): A rotation of 90-90^\circ (or 270270^\circ) about the origin transforms a point (x,y)(x, y) to (y,x)(y, -x). Applying this to (X,y)(-X, y), we get (y,(X))=(y,X)(y, -(-X)) = (y, X), which is not (X,y)(X, -y).
(b) R(O,90)R(O, 90^\circ): A rotation of 9090^\circ about the origin transforms a point (x,y)(x, y) to (y,x)(-y, x). Applying this to (X,y)(-X, y), we get (y,X)(-y, -X), which is not (X,y)(X, -y).
(c) R(O,180)R(O, 180^\circ): A rotation of 180180^\circ about the origin transforms a point (x,y)(x, y) to (x,y)(-x, -y). Applying this to (X,y)(-X, y), we get ((X),y)=(X,y)(-(-X), -y) = (X, -y), which is what we want.
(d) R(O,360)R(O, 360^\circ): A rotation of 360360^\circ about the origin transforms a point (x,y)(x, y) to (x,y)(x, y). Applying this to (X,y)(-X, y), we get (X,y)(-X, y), which is not (X,y)(X, -y).
Therefore, the rotation that transforms (X,y)(-X, y) to (X,y)(X, -y) is a rotation of 180180^\circ about the origin.

3. Final Answer

(c) R (O, 180°)

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