37. Five mark exercise problem XIII

If the angle of elevation of a cloud from a point '$h$' meters above a lake is $\theta_1$ and the angle of depression of its reflection in the lake is $\theta_2$. Prove that the height that the cloud is located from the lake is $\frac{h(tan \ \theta_1 + tan \ \theta_2)}{tan \ \theta_2 - tan \ \theta_1}$.