# My Favorite One-Liners: Part 11

In this series, I’m compiling some of the quips and one-liners that I’ll use with my students to hopefully make my lessons more memorable for them.

Every once in a while, I’ll cover a theorem in class that looks utterly surprising to students at first glance. For example, in trigonometry, I might state that

$\sin^{-1} \left( \sin \pi \right) \ne \pi$,

so that the inverse function doesn’t quite behave like it’s supposed to (because of the restricted domain used to define inverse sine.)

Before explaining why $\sin^{-1} \left( \sin \pi \right)$ isn’t equal to $\pi$, I’ll get the discussion started by saying, “Don’t believe me? Just watch.”… a tip of the cap to this recent hit song (at the time of this writing, the third-most watched video on YouTube).

While on this topic, I have to tip my cap to Kelli Hauser, a sixth-grade teacher in my city who made the following motivational video for students about to take their end-of-year high-stakes test (called, here in Texas, the STAAR exam).

One more parody concerning a recent spacecraft that visited Pluto:

For further reading, here’s my series on inverse functions.

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