SOLUTION
From the image in the question, we can see that it is a right triangle problem.
And we can use the Pythagoras theorem to solve for the length of cable wire needed.
Pythagoras theorem states that:

![\begin{gathered} x^2=16+9 \\ x^2=25 \\ \text{Take the square roots of both sides:} \\ \sqrt[]{x^2}=\sqrt[]{25} \\ x=5ft \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/5k2vrw7uq9rapb64dwsgp5tqst6nkg3uoo.png)
Final Answer:
A cable of length 5 feet is needed.