}{ED},\qquad \frac{\sin 24^\circ}{BD}=\frac{\sin(B/2)}{ED}, $$ hence $$\frac{\sin(B/2)}{\sin(C/2)}=\frac{\sin(24^\circ)}{\sin(18^\circ)}\cdot\frac{CE}{BD}=\frac{\sin(24^\circ)}{\sin(18^\circ)}\cdot\frac{\frac{ab}{a+c}}{\frac{ac}{a+b}}=\frac{\sin(24^\circ)}{\sin(18^\circ)}\cdot\frac{\sin B}{\sin C}\cdot\frac{\sin(A)+\sin(B)}{\sin(A)+\sin(C)}$$ leads to a trigonometric equation in $\sin(\alpha)=\sin(B/2)$, since $\frac{C}{2}=42^\circ-\frac{B}{2}$ and $\sin(A)$ is known.