How do you do this, I think it might be that a^2 + b^2 stuff but I’m not sure

Solution
Note: Sine Rule
[tex]\frac{a}{sinA}=\frac{b}{sinB}=\frac{c}{sinC}[/tex]From the question, we have
[tex]\begin{gathered} \frac{22}{sin31}=\frac{b}{sin66} \\ \\ b=\frac{22sin66}{sin31} \\ \\ b=39.0 \end{gathered}[/tex]The answer is