17. Find the height of the mountain

A girl is flying in a parachute. She observes the top of the mountain at an angle of elevation of 30$^{\circ}$ and the bottom of the mountain at an angle of depression of 60$^{\circ}$, If a line drawn straight beneath the parachute, the distance from the point to the mountain is 813 $m$, then the height of the mountain is 1877.5161408.116469.4813 $m$.

 

(Note: Use $\sqrt{3} = 1.732$)