Question Number 150482 by mathdanisur last updated on 12/Aug/21
$$\frac{\mathrm{1}}{\mathrm{cos}^{\mathrm{4}} \:\frac{\boldsymbol{\pi}}{\mathrm{7}}}\:\:+\:\:\frac{\mathrm{1}}{\mathrm{cos}^{\mathrm{4}} \:\frac{\mathrm{2}\boldsymbol{\pi}}{\mathrm{7}}}\:\:+\:\:\frac{\mathrm{1}}{\mathrm{cos}^{\mathrm{4}} \:\frac{\mathrm{3}\boldsymbol{\pi}}{\mathrm{7}}}\:\:=\:\:? \\ $$
Commented by liberty last updated on 13/Aug/21
$$=\mathrm{374} \\ $$
Commented by mathdanisur last updated on 13/Aug/21
$$\mathrm{Thanks}\:\mathrm{Ser},\:\mathrm{how}.? \\ $$