Question Number 40888 by prof Abdo imad last updated on 28/Jul/18
$$\left.{prove}\:{that}\:\forall\xi\:\in\right]\mathrm{0},\pi\left[\right. \\ $$$$\mid\int_{\xi} ^{\pi} \left(\frac{{sint}}{{t}}\right)^{{n}} {dt}\mid\leqslant\pi\left(\frac{{sin}\xi}{\xi}\right)^{{n}} \:\:{n}\:{integr}\:{natural} \\ $$