This video covers the situation where you have two circles and you're supposed to classify them. If the circles themselves are tangent, they can be "internally" or "externally" tangent. More common is that a segment is tangent to both circles, and you're supposed to know if that "common tangent" is internal or external.
This video is a quick summary of the theorems you should know for tangents to circles, whether you're working problems or looking for hints for your next proof.
Circle Tangent Problems
This is a long video because there's a lot of ground to cover! I work all the most common types of questions, involving both the fact that tangents are perpendicular to the radius they intersect as well as problems where you have to solve for the length of tangents.
Tangents & Inscribed Angles
This is a short video, but it's an important one that addresses the hardest-to-spot tangent problems: the ones where they give you the length of an arc. If you're not on the lookout, you won't realize that arc is inscribed by an angle where one side is a tangent to the circle!
First off we'll review the theorems for tangents, then we'll prove the one about how tangents from a single point are congruent. Hint: congruent triangles are involved.
If you do not have an account, you should get one, because it is awesome! You can save a playlist for each test or each chapter, and save your "greatest hits" into a "watch right before the final" list (not that we recommend cramming, but when in Rome...)