To find angle $ \alpha $ use formula:

$$ A = \dfrac{ a \cdot a \cdot \sin( \alpha ) }{ 1 } $$

After substituting $A = 214\, \text{cm}$, $a = 16\, \text{cm}$ and $a = 16\, \text{cm}$ we have:

$$ 214\, \text{cm} = \dfrac{ 16\, \text{cm} \cdot 16\, \text{cm} \cdot \sin( \alpha ) }{ 1 } $$ $$ 214\, \text{cm} = \dfrac{ 256\, \text{cm}^2 \cdot \sin( \alpha ) }{ 1 } $$ $$ 214\, \text{cm} \cdot 1 = 256\, \text{cm}^2 \cdot \sin( \alpha ) $$ $$ 214\, \text{cm} = 256\, \text{cm}^2 \cdot \sin( \alpha ) $$ $$ \sin( \alpha ) = \dfrac{ 214\, \text{cm} } { 256\, \text{cm}^2 } $$ $$ \sin( \alpha ) = \frac{ 107 }{ 128 }\, \text{cm}^-1 $$ $$ \alpha = \arcsin \left( \frac{ 107 }{ 128 }\, \text{cm}^-1 \right)$$ $$ \alpha \approx 56.7136^o $$

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