5. Alternate Segment Theorem
Turn on the first checkbox: Line DE is a tangent line to the circle, perpendicular to radius OA.
Turn on the second checkbox: Chord AB runs from the tangent line at A to some point B on the circumference of the circle. This cuts the circle into a two segments.
Turn on the third checkbox: Angle BCA is the angle subtending the chord AB from point C in the alternate segment.
What do you notice about and ?
Move around the points B and C to confirm this relationship?
What can you infer about the relationship between and ?
Mark the checkbox to confirm the relationship between the two angles.
How would you describe the location of these angles relative to one another?
Try to prove the relationship. The auxiliary construction lines may help if you need support.