Very few rotations will take the strip to itself.

**Centers:**- Where can the center of rotation be if
the rotation takes the strip to itself?
*If the center is not in the middle of the strip, think about a circle through that center just touching one edge of the strip but not the other. What happens under the rotation to points near that circle?* **Angles:**- Suppose the center of rotation is
on the midline
*y*=0. What angles of rotation are possible if all points of the strip are to go to points on the strip?*Think about points near a circle just touching both edges of the strip.*