Suppose a 6-Ft Person Wishes to Determine the Height of a Footbridge

Suppose a 6-ft person wishes to determine the height of a footbridge connecting two buildings, as shown in the figure below. To do this, this person stands at one end of the bridge (point S) and looks down to a point directly below the other end (point T) . With the help of a companion, point P is determined to form two triangles. Find the height of the footbridge, if ft and ft. ​ ​

A) 9 ft
B) 6 ft
C) 72 ft
D) 8 ft
E) 48 ft