A right triangle is given and it is required that you find the unknown length.
Let the length of the unknown be x.
The right triangle is shown below:
Recall the Pythagorean Theorem which states that in a right triangle, the relationship between the lengths of legs a and b and the length of the hypotenuse, c is:

Substitute the side lengths provided into the equation:

Solve the resulting equation for x:
![\begin{gathered} \Rightarrow x^2=74^2-70^2 \\ \Rightarrow x^2=5476-4900=576 \\ \Rightarrow x^2=576 \\ \text{Take square root of both sides:} \\ \Rightarrow x=\sqrt[]{576}=24 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/a5wddpp720znu1s8t8yb8b5qfoletct2xr.png)
Hence, the required unknown length is 24 ft