Answer:
[tex]\large\boxed{ 79.1ft}[/tex]
Explanation:
The guy-wire, the highest point of the cell phone tower, and the the point on the ground that is 25 ft from the base of the tower form a right triangle, where:
Since you know the lengths of both legs, you can use Pythagora's theorem to find the hypotenuse (the lenght of the guy-wire):
[tex]hypotenuse^2=(leg_1)^2+(leg_2)^2[/tex]
[tex]hypotenuse^2=(75ft)^2+(25ft)^2[/tex]
[tex]hypotenuse^2=5,625ft^2+625ft^2=6,250ft^2[/tex]
[tex]hypotenuse=\sqrt{6,250ft^2}\approx 79.06ft\approx 79.1ft[/tex]