## Calculus 10th Edition

$\lim\limits_{x\to\pi}\cos{3x}=-1.$
Using both Theorems $1.6$ and $1.5: \lim\limits_{x\to c}(f(g(x)))=f(\lim\limits_{x\to c}g(x)):$ $\lim\limits_{x\to\pi}\cos{3x}=\cos{(\lim\limits_{x\to\pi}3x)}=\cos{3\pi}=-1.$