According to our teacher, order of rotational symmetry can never be 1.
It's either 0, 2 or 4.
And that image only turned back to it's position after one whole turn,
and...
EVERY IMAGE TURNS BACK TO ITSELF AFTER THE COMPLETE 360 deg,
So, the order or rotational symmetry was 0?
And the sinx-cosx=0.5, what do you suppose can be the range of the answers?
Also, what equation of line did you get in the intersecting lines one, the lat part?