To find side $ b $ use Law of Cosines:
$$ b^2 = a^2 + c^2 - 2 \cdot a \cdot c \cdot \cos( \beta ) $$After substituting $a = 490$, $c = 524$ and $\beta = 75^o$ we have:
$$ b^2 = 490^2 + 524^2 - 2 \cdot 490 \cdot 524 \cdot \cos( 75^o ) $$ $$ b^2 = 240100 + 274576 - 2 \cdot 490 \cdot 524 \cdot \cos( 75^o ) $$ $$ b^2 = 514676 - 2 \cdot 256760 \cdot \cos( 75^o ) $$ $$ b^2 = 514676 - 513520 \cdot 0.2588 $$ $$ b^2 = 514676 - 132908.756 $$ $$ b^2 = 381767.244 $$ $$ b = \sqrt{ 381767.244 } $$$$ b \approx 617.8732 $$