As shown in the figure:
The two cables and the ground like as an equilateral triangle
The length of each side = 14 m
The pole is perpendicular to the ground
So, there are two right angle triangle
From the left side triangle:
hypotenuse = 14 m
And the length from the cable to the pole = 14/2 = 7 m
Let the height of the pole = h
Using Pythagorean theorem:
So, the height of the pole = 7√3 meters.