Question Number 144509 by phally last updated on 26/Jun/21
$$ \\ $$$${S}_{{n}} =\frac{{Cos}\mathrm{1}}{\mathrm{1}^{\mathrm{2}} }+\frac{{Cos}\mathrm{2}}{\mathrm{2}^{\mathrm{2}} }+\frac{{Cos}\mathrm{3}}{\mathrm{3}^{\mathrm{2}} }+...+\frac{{Cosn}}{{n}^{\mathrm{2}} } \\ $$$${Indicates}\:{that}\:{S}_{{n}\:} \:{is}\:{a}\:{cauchy}\:{suite}? \\ $$