[Sabertooth]

Can it reach 90 degrees, or is that approached as a limit?

Yes, it can reach 90 degress at all three angles on a sphere.

Consider drawing two line segments southward from the North Pole, with a 90 degree angle between them, until they reached the Equator. The angles of the intersections of those lines at the Equator would also be 90 degrees, giving you three at 90.

[samtheman]

You are right. So it doesn't have to be a small sphere. Any size sphere will do.

Thanks for the correction. I stand enlightened!