$ \text{A.} $ $\frac{l \sin \alpha \cos \beta}{\sin (\beta-\alpha)}+h$
$ \text{B.} $ $\frac{l \cos \alpha \cos \beta}{\sin (\beta-\alpha)}+h$
$ \text{C.} $ $\frac{l \cos \alpha \sin \beta}{\sin (\beta-\alpha)}+h$
$ \text{D.} $ $\frac{l \sin \alpha \sin \beta}{\sin (\beta-\alpha)}+h$