Think of Q as a rotation. How many of these rotations are required to get back to where you started? After that, it's just modular arithmetic.
Q is in 2x2 matrix form, Q= (0, -1, 1, 0)
Using geometrical reasoning only, state the smallest possible values of k given that:
See, I know how to get the answer, I just don't know how to explain it using geometrical reasoning.