1. The problem states that $DF = DE + EF = 11 + 4 = 15$ meters, but the length is given as 11.7 meters without using the hypotenuse formula. 2. This suggests that $DF$ is the sum of two segments $DE$ and $EF$, which are 11 m and 4 m respectively. 3. Adding these segments directly gives $DF = 11 + 4 = 15$ m. 4. However, the problem mentions $DF$ is 11.7 m, which implies $DF$ is not a straight sum but likely the hypotenuse of a right triangle formed by $DE$ and $EF$. 5. The hypotenuse formula is $DF = \sqrt{DE^2 + EF^2} = \sqrt{11^2 + 4^2} = \sqrt{121 + 16} = \sqrt{137} \approx 11.7$ m. 6. Since the problem says not to use the hypotenuse formula, the direct sum $15$ m is the length along the path $DE + EF$, but the straight-line distance $DF$ is approximately $11.7$ m. Final answer: The length $DF$ as the sum of segments is $15$ m, but the straight-line distance (hypotenuse) is approximately $11.7$ m.