The angle between two radii of the same circle?

There are always two angles between two radii of the same circle ... starting at one of them

and going each direction to the other one.

If you define the angle between them as the smaller of the two angles, then it can be anything

between 0° and 180°.

If you define it as the larger of the two, then it can be anything between 180° and 360°.

If you don't care which of the two angles is measured, then it can be anything between 0° and 360°.