tolong bantu ya, Terima kasih

Mapel : Matematika
Bab : Bangun Ruang Sisi Lengkung

Kerucut

Keliling = 2 x π x r
  66 cm = 2 x 22/7 x r
  66 cm = 44/7 x r
          r = 66 x 7/44
          r = 10,5 cm

Volume kerucut
= 1/3 x π x r² x t
= 1/3 x 22/7 x 10,5 cm x 10,5 cm x 30 cm
= 3.465 cm³