To find leg $ a $ use formula:
$$ \tan \left( \alpha \right) = \dfrac{ a }{ b } $$After substituting $ \alpha = 37^o $ and $ b = 16 $ we have:
$$ \tan( 37^o ) = \dfrac{ a }{ 16 } $$ $$ 0.7536 = \dfrac{ a }{ 16 } $$$$ a = 0.7536 \cdot 16 $$$$ a = 12.0569 $$