To find leg $ a $ use formula:
$$ \sin \left( \alpha \right) = \dfrac{ a }{ c } $$After substituting $ \alpha = 15^o $ and $ c = 37 $ we have:
$$ \sin( 15^o ) = \dfrac{ a }{ 37 } $$ $$ 0.2588 = \dfrac{ a }{ 37 } $$$$ a = 0.2588 \cdot 37 $$$$ a = 9.5763 $$