question_answer

From a place which is 20 m above the ground, the angle of elevation and depression of the top and foot of a building are \[30{}^\circ \] and \[45{}^\circ \] respectively. The height of building is:

A)  \[\left( 20+\frac{20}{\sqrt{3}} \right)\,\,\,m\]       

B)  \[\left( 20-\frac{20}{\sqrt{3}} \right)\,\,\,m\]

C)  \[\left( 20+20\,\sqrt{3} \right)\,\,\,m\]      

D)  \[\left( 20-20\,\sqrt{3} \right)\,\,\,m\]

E)  None of these