Surface area = 2419.34 square meters
Solution:
The base is a heptagon. It have 7 sides.
Area of base (B) = [tex]\frac{7}{2}ar[/tex]
[tex]$=\frac{7}{2}\times11\times11.42[/tex]
Area of base (B) = 439.67 m²
Perimeter of base (P) = Number of sides × side length of base
= 7 × 11
Perimeter of base (P) = 77 m
Distance between bases = 20 m
Surface area of the prism = 2B + PH
= 2 × 439.67 + 77 × 20
= 879.34 + 1540
= 2419.34 m²
Surface area = 2419.34 square meters