Yes, I used d2. I don't understand why the distance d2 can't give the energy from friction. I take a dot fixed on the wall at start (45°), and I measured the distance between that dot and the new dot of contact (at 46° or less). Could you explain more please ? and how can I draw it on the drawing ?How did you calculate that? If using your d2, then it is wrong.
I suppose you mean "work" from friction because I used d2 for that. I used the physical materials: the wall and the circle. When the circle moves, the angle between the wall and the circle changes (when I'm on the circle, I see the wall rotates) and the friction has less distance to move because there is a slip due to the modification of that angle.Work is determined by the motion of the physical material to which the force is applied