Question Number 77729 by aliesam last updated on 09/Jan/20 | ||
$${prove}\:{that} \\ $$ $$\int_{−\pi} ^{\pi} {cos}\left(\mathrm{2}{x}\right)\:{cos}\left(\mathrm{3}{x}\right)\:{cos}\left(\mathrm{4}{x}\right)....{cos}\left(\mathrm{2005}{x}\right){dx}>\mathrm{0} \\ $$ | ||