To find the segment AB you have to use the formula
[tex]S=\text{ }\frac{\theta}{180}\pi R[/tex]
S is the the arch, in this case segment AB
θ is the central angle θ=80º
R is the radius R=8m
I'll use π= 3.14
[tex]S=\frac{80}{180}\cdot3.14\cdot8[/tex]
S= 11.164 ≅ 11.2m
