Question Number 99625 by Kalam last updated on 22/Jun/20
$$\mathrm{If}\:\:{f}\left({x}\right)=\mathrm{cos}^{\mathrm{2}} {x}\:+\:\mathrm{sec}^{\mathrm{2}} {x},\:\mathrm{its}\:\mathrm{value} \\ $$$$\mathrm{always}\:\mathrm{is} \\ $$
Answered by maths mind last updated on 22/Jun/20
$${cos}^{\mathrm{2}} \left({x}\right)+\frac{\mathrm{1}}{{cos}^{\mathrm{2}} \left({x}\right)}\geqslant\mathrm{2} \\ $$$${value}\:\in\left[\mathrm{2},+\infty\left[\right.\right. \\ $$