1. In which direction is a rotation with a negative angle of rotation ?
Negative rotations are clockwise, positive rotations are anti-clockwise around the centre of rotation.
2. What is a half turn rotation?
A half turn rotation is a rotation of 180o.
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. What happens if we rotate an object through an angle of 360o?
We get back to where we started from!