To find the length of the cable, we can use the Pythagorean theorem. The setup can be visualized as a right triangle, where:
- The height of the pole (the height where the cable is attached) is one side of the triangle (20 ft).
- The distance from the base of the pole to the point where the cable is anchored on the ground is the other side (10 ft).
- The cable itself is the hypotenuse.
Using the Pythagorean theorem, which states that \( a^2 + b^2 = c^2 \) (where \( c \) is the hypotenuse), we can substitute the values into the equation:
\[ a = 20 , \text{ft} \ b = 10 , \text{ft} \]
Calculating:
\[ 20^2 + 10^2 = c^2 \]
\[ 400 + 100 = c^2 \]
\[ 500 = c^2 \]
Now taking the square root to find \( c \):
\[ c = \sqrt{500} \approx 22.36 , \text{ft} \]
Rounding to the nearest tenth, the length of the cable is approximately 22.4 ft.
So the correct answer is 22.4 ft.