9. Solve the equation $12 \sin x-5 \cos x=13$.

$$
12 \sin x-5 \cos x=13
$$
Solution: $\sqrt{12^{2}+5^{2}} \sin \left(x-\operatorname{arctg} \frac{5}{12}\right)=13, x-\operatorname{arctg} \frac{5}{12}=\frac{\pi}{2}+2 \pi k$.