Why one can split curved surface using non-touching circles?

Hi, I made holes on a sphere using Evaluate Surface(Frame) → Surface Split method.

The circles were drawn on the planes provided by Evaluate Surface(Frame) based on the points exactly on the surface of the sphere. So I think the planes are tangent to the sphere therefore the circles either.

If the edges of the circles don’t touch the surface at all then I don’t understand why the circles can be cutters in this case.

My English is not good, hope I made myself clear.
Thanks!

I guess same behavior as Trim command with apparent intersections ON?

1 Like