To determine the rotation that takes the point \( P(-1, 2) \) to the point \( P'(2, 1) \), we can analyze the points.
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First, calculate the change in coordinates:
- The original point is \( P(-1, 2) \).
- The new point is \( P'(2, 1) \).
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To see how the rotation is performed, we can visualize the transformation:
- The point \( P \) lies in the second quadrant, and \( P' \) lies in the first quadrant.
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Observe the movement:
- The x-coordinate increases from -1 to 2 (a total of 3 units right).
- The y-coordinate decreases from 2 to 1 (a total of 1 unit down).
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Analyzing the rotation:
- The rotation that would move \( P \) to \( P' \) can now be identified as a 90° clockwise rotation.
Accordingly, the correct description of the rotation is:
- 90 degrees rotation (clockwise).
Therefore the answer is \( 90\text{° rotation} \).