Question Number 31464 by abdo imad last updated on 08/Mar/18
$$\left.\mathrm{1}\right)\:{find}\:\:{A}_{{n}} =\:\int_{\mathrm{0}} ^{\frac{\pi}{\mathrm{2}}} \:\:{e}^{−{x}} {cos}\left({nx}\right){dx} \\ $$$$\left.\mathrm{2}\right)\:{find}\:\:{S}_{{n}} =\:\sum_{{k}=\mathrm{0}} ^{{n}} \:{A}_{{k}} \:\:. \\ $$