We split the 80 m cable in half and work 1/2 of the problem

y = a Cosh (x / a) -a

We draw x and y axis

coordinate of top of the pole would be (x, 30)

30 = a Cosh(x / a)-a

first equation: (30 – a) / a = Cosh(x/a)

a sinh (x/a) = 40

second equation = sinh(x/a) = 40 / a

We use : cosh ^{ 2 } (t) – sinh ^{ 2 } (t) = 1

(( 30 + a) / a ) ^{ 2 } – (40 / a) ^{ 2 } = 1

(30 + a)^{ 2 } – (40 )^{ 2 }= a ^{ 2}

a = 11.67

11.67 * sinh( x / 11.67) = 40

sinh( x / 11.67) = 3.427

asinh( sinh ( x / 11.67) = asinh( 3.427 )

x / 11.67 = 1.945

x = 22.7 m is one half of the value. The poles are 45.4 meters apart