Question

1-2sin^2(22градусов 30 минут)

Answer 1

$cos2alpha=1-2sin ^{2} alpha$

$22^{o}30'}=22,5 ^{o}$

$1-2sin^{2}(22^{o}30')=cos(2*22,5 ^{o})=cos45^{o}=frac{sqrt2}{2}= frac{1}sqrt2{}$