Question

Luas permukaan tabung 48πcm. jika tinggi tabung 10 cm, tentukan volumenya

Answer 1

Lp = 48π
2πr.(r+t) = 48π
r.(r+10) = 48π:2π
r^2 + 10r = 24
r^2 + 10r - 24 = 0
r^2 + 12r - 2r - 24 = 0
r(r+12) - 2(r+12) = 0
(r+12)(r-2) = 0
r = -12 atau r = 2 (memenuhi)

V = π . r^2 . t
V = π . 2^2 . 10
V = 40π cm3