I think you’re misunderstanding. Yes, it cannot fit in when it’s angled properly to fit into the hole. However, if you angle the plate 45 degrees and lift one end of the plate, it will fall into the diagonally. That’s why manholes are round shaped. There is no angle for a round cover to fall into the hole itself.
The problem is the hole is smaller than the cover. If they were the same size it would fall though
I think you’re misunderstanding. Yes, it cannot fit in when it’s angled properly to fit into the hole. However, if you angle the plate 45 degrees and lift one end of the plate, it will fall into the diagonally. That’s why manholes are round shaped. There is no angle for a round cover to fall into the hole itself.
You are right, never mind. I was thinking Pythagorean theorem