Question Number 62434 by mathsolverby Abdo last updated on 21/Jun/19
$${let}\:{f}\left({x}\right)={ch}\left({cosx}\right) \\ $$$$\left.\mathrm{1}\right){calculste}\:{f}^{\left({n}\right)} \left({x}\right)\:{and}\:{f}^{\left({n}\right)} \left(\mathrm{0}\right) \\ $$$$\left.\mathrm{2}\right){developp}\:{f}\:{at}\:{integr}\:{serie} \\ $$