The angle of elevation of the top of a building from the foot of a tower is 30° and the angle of elevation of the top of the tower from the foot of the building is 60°. If the tower is 50 m high, then the height of the building is:
1
\(\dfrac{51}{3}\:m\)
2
\(\dfrac{49}{3}\:m\)
3
\(\dfrac{50}{3}\:m\)
4
\(\dfrac{47}{3}\:m\)