Answer:
4.5 m
Explanation:
Distance from center to the the bottom part where headroom begins is 3.9 m-2.6 m=1.3 m
Since the radius is 2.6 m and acts as hypotenuse(see attached image), then the other length will be
![\sqrt {2.6^(2)-1.3^(2)=5.07}=2.25166605](https://img.qammunity.org/2020/formulas/mathematics/middle-school/c84wnhkqil6lgdev9kdmjzc6aefwvt8s1m.png)
Approximately 2.25 m
The half width is 2.25 m hence full width will be 2.25*2=4.5 m