5.5 The Substitution Rule/21

$\int {\frac {\cos {({\sqrt {t}})}}{\sqrt {t}}}dt=\int {\sqrt {u}}$

${\begin{aligned}u&={\sqrt {u}}\\[2ex]du&=\pi \;dx\\[2ex]{\frac {1}{\pi }}du&=dx\end{aligned}}$