Usually they’re wedge-shaped, though I have no idea what the correct term for wedge-shaped might be. Segment with arc?? Whatever. Pie-shaped.
But this isn’t about geometrical terms or determining the area of anything.
It’s about seeing things in fresh, new ways.
Whoever it was that amended this sign needed only a single line to alter it completely.
I don’t think I will ever again be able to see a no-smoking symbol without considering the wonders of pie.