To find the length of the yellow segment, we have to use Pythagorean's Theorem. But first, we have to find the length of the black line at the bottom.

Where a = 4ft and b = 9ft.
![\begin{gathered} c^2=4^2+9^2 \\ c^2=15+81 \\ c=\sqrt[]{96} \\ c\approx9.8 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/7u6ahl4x9arcf82knopdv5kjsd4fjscehw.png)
So, the length of the black segment is 9.8 feet.
Now, we find the yellow line length

Where a = 4 and b = 6.
![\begin{gathered} c^2=4^2+6^2 \\ c^2=16+36 \\ c^2=52 \\ c=\sqrt[]{52} \\ c\approx7.2 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/34fimha3w056a79iy9re7udeotc3t423zl.png)
Therefore, the length of the yellow line is 7.2 feet.