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a)
$\cos\alpha=\frac{19{,}5}{22{,}1}\parallel\cos^{-1}$
$\alpha=28{,}0724..°\approx28{,}1°$
b)

$A=\frac{ah}{2}$

$\tan40°=\frac{h}{3{,}0}$
$h=3\tan40°$
$h=2{,}5172...cm$

$A=\frac{6{,}0\cdot2{,}5172...}{2}=7{,}55189...cm^2\approx7{,}6cm^2$