Alternate Segment Theorem

[JamieLeaf]

Hey guys,
How do I tell when the alternate segment theorem exists in a circle geometry problem? Thanks!!

[RuiAce]

This theorem essentially involves a tangent, and a triangle inside a circle.

Suppose we have a triangle in a circle. If there is a tangent drawn on the circle, at one of the vertices of the triangle, then we can use the alternate segment theorem. (But make sure to not use it on the wrong angles.)