suatu kerucut panjang jari jarinya 7 cm dan tingginya 9 cm jika panjang jari jarinya diperpanjangtiga kalinya tentukan perubahan volumenya

Volume semula = 1/3 x 22/7 x 7 x 7 x 9
= 1/3 x 22 x 7 x 9
= 1/3 x 154 x 9
= 154 x 3
= 462 cm 3
Volume 2 = 1/3 x 22/7 x 343 x 343 x 9
= 1/3 x 22 x 49 x 343 x 9
= 1/3 x 1070 x 343 x 9
= 1/3 x 367010 x 9
= 367010 x 3
= 1101030 cm 3

DIK=r =7cm diperpanjang 3kalinya =7×3=21cm.
t = 9 cm.
jawab = v =1/3Πr²t
= 1/3×22/7×21²×9
=1/3×22/7×441×9
=1/3×22×63×9 (7 sma 441 dicoret=63)
= 12,474 / 3 = 4,158 cm