Lungimea cercului =
[tex]2 \: \pi \: r[/tex]=> 12pi = 2pi• r => r = 12÷2 = 6 cm
V = [tex] \frac{4 \: \pi \: {r}^{3} }{3} [/tex]
= [tex] \frac{4\pi {6}^{3} }{3} [/tex]
= [tex] \frac{4\pi \times 216}{3} [/tex]
= [tex]4\pi \times 72[/tex]
= [tex]288\pi \: cm {}^{3} [/tex]
