Try this
Adjust the

angle below by dragging an orange dot and see how the angle

∠ABC behaves.
Note that it is a full angle only when it is exactly 360°

Not widely used. If you continue to increase an angle it will eventually 'double back' on itself and form a full 360° angle. This is the Full Angle.
One could argue that this is the same as a zero-sized angle. But we generally mean the reflex angle and so it is a full circle or 360°.
Adjust the angle above and try to create the full angle going around in both directions.

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