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What points do I graph the image of the rotation on?

What points do I graph the image of the rotation on?-example-1

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Answer:

see attached

Explanation:

No doubt you have seen that the tranformation that rotates a figure 270° CCW is the same as the one that rotates a figure 90° CW:

(x, y) ⇒ (y, -x)

This means the coordinate A(-3, 1) rotates to the position A'(1, 3). In this figure, that happens to coincide with point B.

When I drew this figure and the center of rotation O(0, 0), I was a little surprised to see the four points form a square. That makes it unsurprising that the point A gets rotated to point B by the desired transformation. (When you rotate a square 90° (or 270°) about one corner, an adjacent vertex (corner) will line up with the other adjacent vertex (corner).

_____

If you need to get a feel for rotations, so you can do this better in the future, it might be helpful to trace the figure (and the axes) onto a piece of tissue paper or tracing paper, then rotate it the necessary amount and see where the figure ends up.

This exercise may be easier with a print of the figure, but you can do it on a computer screen, too. (A touch screen makes it more difficult.)

What points do I graph the image of the rotation on?-example-1
User BigDX
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