b. Tentukan perbandingan volume B dengan volume C.
Vb/Vc = (19/3 πr²t) / (⅓ π.rc².tc - ⅓ π.rd².td)
Vb/Vc = (19/3 πr²t) / (⅓ π.(2r)².2t - ⅓ π.(1r)².1t)
Vb/Vc = (19/3 πr²t) / (⅓ π.4r².2t - ⅓ π.r².t)
Vb/Vc = (19/3 πr²t) / (8/3 πr²t - ⅓ πr²t)
Vb/Vc = (19/3 πr²t) / (7/3 πr²t) = 19/3 : 7/3
c. Tentukan perbandingan volume C dengan volume D.
Vc/Vd = (7/3 πr²t) / (⅓ π.rd².td)
Vc/Vd = (7/3 πr²t) / (⅓ π.(1r)².1t)
Vc/Vd = (7/3 πr²t) / (⅓ π.r².t)
Vc/Vd = (7/3 πr²t) / (⅓ πr²t) = 7/3 : 1/3
14. Untuk tiap pasangan bangun ruang yang sebangun, hitung volumeyang belum diketahui (lihat gambar di buku).
a. Soal a
V = ⅓ πr²t
S kerucut kecil (s)/ S kerucut besar (S) = 5/15 = 1/3
r kerucut kecil (r)/ r kerucut besar (R) = 1r/3r
t kerucut kecil (t)/ t kerucut besar (T) = 1t/3t
Vk/Vb = ⅓ πr²t / ⅓ π (3r)² (3t)
Vk/Vb = ⅓ πr²t / ⅓ π (9r²) (3t)
Vk/Vb = ⅓ πr²t / 27/3 πr²t
Vk/Vb = ⅓ / 27/3
Vb = ⅓ / 27/3 x Vk
Vb = ⅓ / 27/3 x 12π
Vb = ⅓ x 3/27 x 12π = 4/9 π