Squeeze theorem

The Twelfth Doctor once used the squeeze theorem to solve a calculus problem. With it, he proved that:

Part of the demonstration made by the Twelfth Doctor. (TV: The Pilot)

$\lim _{\theta \to 0}{\frac {sin\theta }{\theta }}=1$

During the demonstration, the Doctor used mathematical concepts such as sin, cos, inequalities and limit. (TV: The Pilot)

Behind the scenes

Although the name "squeeze theorem" wasn't used, and the demonstration wasn't explained by the Doctor, it is a faily basic calculus theorem, and can be recognised by the viewers.