2. In a triangle, given the three sides $a, b, c$ and the corresponding three interior angles $\alpha, \beta, \gamma$ satisfy $\lg \sin \alpha+\lg \sin \gamma=2 \lg \sin \beta$, then the positional relationship between the lines $x \sin ^{2} \alpha+y \sin \alpha=a$ and $x \sin ^{2} \beta+y \sin \gamma=c$ is
A. Parallel
B. Oblique intersection
C. Perpendicular
D. Coincident
2. A Hint: $\sin \alpha \sin \gamma=\sin ^{2} \beta$. The slopes of the two lines are $k_{1}=-\sin \alpha, k_{2}=-\frac{\sin ^{2} \beta}{\sin \gamma}=-\sin \alpha$. Therefore, $k_{1}=k_{2}$.