I'm assuming that the figure formed in this problem is a right angle. Thus, we need to use the Pythagorean theorem to get the distance or the hypotenuse.
Length = 20 meters
Height = 16 meters
a² + b² = c²
(20m)² + (16m)² = c²
400m² + 256m² = c²
656m² = c²
√656m² = √c²
25.61 m = c
The distance is 25.61 meters.