તો $f(x)$ ની મહતમ કિમંત મેળવો.
$-2\left(\cos ^{2} \mathrm{x}\right)+2\left(2+2 \cos 2 \mathrm{x}+\sin ^{2} \mathrm{x}\right)$
$4+4 \cos 2 \mathrm{x}-2\left(\cos ^{2} \mathrm{x}-\sin ^{2} \mathrm{x}\right)$
$\mathrm{f}(\mathrm{x})=4+\underbrace{2 \cos 2 \mathrm{x}}_{\max =1}$
$\mathrm{f}(\mathrm{x})_{\max }=4+2=6$