There is a park which is in the shape of a right-angled triangle, with a tower erected at the midpoint of the longest edge of the park. The two perpendicular edges of the park subtend angles of 60 degree and 90 degree at the top of the tower. If the area of the park is 648sqrt2 sq. m, what is the height of the tower?

1) 36m
2) 18sqrt3 m
3) 18sqrt2 m
4) 18 m
5) cannot be determined