We are given
total length of cable is 30 feet
and this cable is on hypotenuse sides of the triangles
so, we can draw triangle as
Let's assume those hypotenuse as 'a' and 'b'
so, we will have

now, we can find 'a' and 'b' from triangle
Smaller triangle:

Larger triangle:

we know that

so, we can plug this value
and we get

now, we can solve for x



now, we can use quadratic formula
we get


so,
The point should be located 4.510 feet , 9.627 feet from the smaller pole to use 30 feet cable............Answer