To find leg $ b $ use formula:
$$ \sin \left( \beta \right) = \dfrac{ b }{ c } $$After substituting $ \beta = 70^o $ and $ c = 6 $ we have:
$$ \sin( 70^o ) = \dfrac{ b }{ 6 } $$ $$ 0.9397 = \dfrac{ b }{ 6 } $$$$ b = 0.9397 \cdot 6 $$$$ b = 5.6382 $$