The angle of elevation of the top of a vertical tower standing on a horizontal plane is observed to be 45º from a point A on the plane. Let B be the point 30 m vertically above the point A. If the angle of elevation of the top of the tower from B be 30º, then the distance (in m) of the foot of the tower from the point A is :
(1) 15(1 + √3 )
(2) 15(3 – √3 )
(3) 15(3 + √3 )
(4) 15(5 – √3 )
