[tex]\qquad\qquad\huge\underline{{\sf Answer}}♨[/tex]
let's solve ~
Perimeter of the composite figure :
Perimeter of rectangle + circumference of semi circle - common side.
Perimeter of rectangle :
[tex]\qquad \tt \dashrightarrow \:2(4 + 12)[/tex]
[tex]\qquad \tt \dashrightarrow \:2(16)[/tex]
[tex]\qquad \tt \dashrightarrow \:32 \: \: ft {}^{} [/tex]
Circumference of Semicircle :
[tex]\qquad \tt \dashrightarrow \:\pi r[/tex]
[tex]\qquad \tt \dashrightarrow \:3.14 \times 2[/tex]
[tex]\qquad \tt \dashrightarrow \:6.28 \: ft[/tex]
Length of common side = 4 feet
So, perimeter of composite figure :
[tex]\qquad \tt \dashrightarrow \:32 + 6.28 - 4[/tex]
[tex]\qquad \tt \dashrightarrow \:34.28 \: ft[/tex]
