Resposta :
C = 2 * π * r
--------------------
a) 5cm
C = 2 * 3,14 * 5
C = 31,4
b) 0,61cm
C = 2 * 3,14 * 0,61
C = 3,8308
c) 3,4cm
C = 2 * 3,14 * 3,4
C = 21,352
d) 10cm
C = 2 * 3,14 * 10
C = 62,8
C = 2 * π * r
--------------------
a) 5cm
C = 2 * 3,14 * 5
C = 31,4
b) 0,61cm
C = 2 * 3,14 * 0,61
C = 3,8308
c) 3,4cm
C = 2 * 3,14 * 3,4
C = 21,352
d) 10cm
C = 2 * 3,14 * 10
C = 62,8