Respuesta :

melissaycui
First since you know the radius:3 the perimeter of a full circle would be
2pi x 3 = 6 pi. But since it's only half it would be 3 pi. 

6+3+3+3pi gets you 12+3 pi

tstein12345
The answer would be 21.42cm as 6 + 3 + 3 = 12 and 2*3pi/2 = 3pi
3 pi = 9.42 and so 12 + 9.42 = 21.42 cm.