Question 1148993
<br>
This is a classic problem with a simple answer.  If the heights of the two poles/beams are a and b, and the cables are connected from the top of one to the bottom of the other, then the distance above the ground where the cables cross is<br>
{{{(a*b)/(a+b)}}}<br>
So with the beam lengths 40 and 30 in this problem, the distance above the ground where the cables cross is<br>
{{{(40*30)/(40+30) = 1200/70 = 120/7}}}<br>
It's a good exercise using a bunch of similar triangles to derive that formula....<br>