Answer:
Step-by-step explanation:
use sin formula
[tex]\frac{a}{sin \alpha } =\frac{b}{sin \beta } =\frac{c}{sin \gamma} \\\frac{10}{sin~40} =\frac{12}{sin ~\beta } \\sin~\beta =\frac{12}{10} \times sin~40\\ \beta=sin^{-1}(1.2 sin ~40)\approx 50.5 ^\circ\\\gamma=180-(40+50.5)=89.5^\circ\\\frac{c}{sin~89.5}=\frac{10}{sin~40} \\c=\frac{sin~89.5}{sin ~40} \times 10 \approx 15.6\\D[/tex]
