Réponse :

Explications étape par étape :

Bonjour

1) Aire = pi X2² = 4pi cm^2
  Volume = 4XpiX6 = 24pi cm^3

2) Rayon = 6/2 = 3 cm
   Aire = pi X3² = 9pi cm^2
  Volume = 9XpiX4 = 36pi cm^3

3) Rayon = 50 cm ) 5 dm
  Aire = pi X5² = 25pi cm^2
  Volume = 25XpiX6 = 150pi dm^3

4) Rayon = 9/2mm = 4,5 mm
   Hauteur = 0,4 clm = 4 mm
  Aire = pi X4,5² = 20,25pi mm^2
  Volume = 20,25XpiX4= 81pi mm^3