If you've used L'hopital's rule to solve this calculus limit problem, you've likely made the same mistake I did! Squeeze theorem is where L'hopital's rule comes from and so using it on this limit that is the famous squeeze thereom limit is a big calc 1 mistake...unless you understand why! Derivatives and indeterminate form make solving calculus AB limit problems like these a breeze with L'Hopital's rule, but it's inappropriate to use here. By the end of this video, you'll understand why. We'll use first principle on the formal definition of the derivative of sin x to demonstrate why L'hopital's rule is a trap!

0:00 Introduction
0:26 Plugging in X
0:32 Indeterminate Form
1:00 Using L'Hopital's Rule
2:34 Sin x Derivative Proof (First Principle)