FP1 question:

Can someone explain to me how for part b the answer is N = 8?

Thank you!

Jack

Think about what the angle of rotation A represents and think about how many multiples of that rotation you need to get to a multiple of 360 degrees, which will be the identity matrix.

Remember that if A represents a rotation of $\alpha$ then $A^2$ is a rotation of $\alpha$ followed by a rotation of $\alpha$ for a total rotation of $2\alpha$.

Ahhhh okay right I'm with you - many thanks!!