If the lenght of a circle circumference is given by:
[tex]c = 2\pi \times r[/tex]
So the lenght of a semicircle circumference is given by the half of it:
[tex]c \: (semicircle) = (2\pi \times r) \div 2 \\ c \: (semicircle) =\pi \times r[/tex]
Radius (R) = 12 ft
[tex]c \: (semicircle) =12\pi \: ft[/tex]
Answer = 12pi ft of fence.
