Rotation of a figure

Rotation of a group of points. Move original (blue) points or input coordinates at top left. Use green slider to change angle of rotation. Purple points show the rotation.
Rotation of a figure
How do the x- and y-coordinates of each point change as you rotate 90 degrees? What about 180 degrees?[br][br] If a figure is in quadrant II and is rotated 180 degrees, what quadrant will the rotated figure end up in?

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