Answer:
The length of AB is;
![12\text{ ft}](https://img.qammunity.org/2023/formulas/mathematics/college/akakqzxgrwizx7bruliiv3abqac6yty5ul.png)
Step-by-step explanation:
Given the isosceles trapezoid in the attached image.
The length of line segment AE will be;
![\begin{gathered} AE=(28-12)/(2)=(16)/(2) \\ AE=8\text{ ft} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/xziitat7fvkfatcreudalyubtuhxv3uc3a.png)
We can then use the Pythagorean theorem to solve for the length of the line segment AB;
![\begin{gathered} AB^2=AE^2+BE^2 \\ AB^2=8^2+9^2 \\ AB^2=64+81 \\ AB=\sqrt[]{64+81} \\ AB=\sqrt[]{145} \\ AB=12.04ft \\ AB=12\text{ ft} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/3kq20zdvth3egleadn3s5yh00cs72so72y.png)
Therefore, the length of AB is;
![12\text{ ft}](https://img.qammunity.org/2023/formulas/mathematics/college/akakqzxgrwizx7bruliiv3abqac6yty5ul.png)