AB is a vertical pole with B at the ground level and A at the top. A man finds that the angle of elevation of the point A from a certain point C on the ground is `60o` . He moves away from the pole along the line BC to a point D such that `C D""=""7""m` . From D the angle of elevation of the point A is `45o` . Then the height of the pole is (1) `(7sqrt(3))/2dot1/(sqrt(3)-1)m` (2) `(7sqrt(3))/2dot(sqrt(3)+1)m` (3) `(7sqrt(3))/2dot(sqrt(3)-1)m` (4) `(7sqrt(3))/2dot1/(sqrt(3)+1)m`

Options

A. `(7 sqrt(3))/(2).(1)/(sqrt(3)+1)m`
B. `(7 sqrt(3))/(2).(1)/(sqrt(3)-1)m`
C. `(7 sqrt(3))/(2).(sqrt(3) + 1)m`
D. `(7 sqrt(3))/(2).(sqrt(3)-1)m`

Answer

C