Answer:
628.3 cm
Step-by-step explanation:
The window has a semicircle shape = half of a circle
Perimeter of the window = ½(πr²)
Radius (r) = 20 cm
Plug in the value
Perimeter of the window = ½(π*20²)
= ½(π*400)
Perimeter of the window = 628.31853 ≈ 628.3 cm (nearest tenth)