Răspuns :
[tex]Aria\,bilei=64\pi\,=\, 4\pi{R^2}\;\;\Rightarrow\;\;R^2 = 64\pi:4\pi =\;16\;\;\boxed{R=4};\\
V_{bila}=\frac{4\pi{R^3}}{3}=\frac{4\cdot64}{3}\cdot\pi
[/tex]
A = 64π = 4πr² => r = √64π : 4π => r = 4 cm
V = 4πr³/3 = 4π64/3 = 256/3 ≈ 85,(3) cm³
Obs. Am calculat π = 3,14
V = 4πr³/3 = 4π64/3 = 256/3 ≈ 85,(3) cm³
Obs. Am calculat π = 3,14