Ile centymetrow ma obwod kola o promieniu a)10cm b)2dm c)4m d)20mm e)0,5dm f)0,3m

a)10cm 10cm x 2 x 3,14 = 62,8cm b)2dm 20cm x 2 x 3,14 = 123,6cm c)4m 400 x 2 x 3,14 = 2512cm d)20mm 2 x 2 x 3,14 = 12,56cm e)0,5dm 5 x 2 x 3,14 = 31,4cm f)0,3m 30 x 2 x 3,14 = 188,4cm

a)10cm Ob = 2πr Ob = 2 × π × 10cm Ob = 20π cm b)2dm = 20 cm Ob = 2πr Ob = 2 × π × 20cm Ob = 40π cm c)4m = 400 cm Ob = 2πr Ob = 2 × π × 400cm Ob = 800π cm d)20mm = 0,2 cm Ob = 2πr Ob = 2 × π × 0,2cm Ob = 0,4π cm e)0,5dm = 5 cm Ob = 2πr Ob = 2 × π × 5cm Ob = 10π cm f)0,3m = 30 cm Ob = 2πr Ob = 2 × π × 30cm Ob = 60π cm.