How far are the high voltage pylons standing apart?

Question

A wire with a length of 60 m is hanging between two high voltage pylons.
The wire is connected to the pylons at a height of 50 m.
The middle part of the wire is 20 m above the ground level.
How far are the high voltage pylons standing apart?

Answer 1

Using the formula for a catenary s=sinh(x/c)
Where s=60, c=20 and x is distance of mid point to pole
60=20sinh(x/20)
3=sinh(x/20)
Sinh-1 (3) = x/20 =1.81845 (5 d.pl.)
X=20x1.81845 = 36.37 (2 d. pl)
Distance between poles = 2x = 72.74 metres(2 d. pl)