Circle Geometry: Proving AB=CD with Intersecting Lines

Question

M is the center of the circle.

Perhaps $AB=CD$

00:00 Is AB equal to CD?

00:03 CD is a diameter - a chord passing through the center of the circle

00:09 Any chord that is not a diameter is shorter than the circle's diameter

00:13 AB is a chord that is not a diameter, therefore it must be shorter than the diameter

00:16 And this is the solution to the question

CD is a diameter, since it passes through the center of the circle, meaning it is the longest segment in the circle.

AB does not pass through the center of the circle and is not a diameter, therefore it is necessarily shorter.

Therefore:

$AB\ne CD$