The angle of elevation of the top of vertical tower standing on a horizontal plane is observed to be 45° 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 30°, then the distance (in m) of the foot of the tower from the point A is:
1
15 (3 - √3)
2
15 (3 + √3)
3
15 (1 + √3)
4
15 (5 - √3)