1. Which way is a rotation with a negative angle of rotation ?

Negative rotations are clockwise, positive rotations are anti-clockwise.

2. What is a quarter turn rotation?

A quarter turn rotation is a rotation of 90o (anti-clockwise).

3. How many points are invariant (do not move) under rotations?

There is only one invariant point under a rotation. That is the centre of rotation.

4. Is a rotation an isometry?

Yes. The size and shape of the image and the object remain the same under a rotation.

5. What happens if we rotate an object through an angle of 360o?

We get back to where we started from!