19. Determine the height of the lighthouse

From the top of an apartment of height 21 \(m\), a boy observes the top of the lighthouse at an angle of elevation of 45\(^{\circ}\) and the bottom of the lighthouse at an angle of depression of 30\(^{\circ}\). Find the height of the lighthouse.

 

Answer:

 

The height of the lighthouse is 2136.37257.37256.372 \(m\).