[tex]s = \pi rl[/tex]

1) ≈ 373,85 см³

r = 14 ÷ 2 = 7 см

[tex]s = 7 \times 17\pi = 119\pi = 373.85... \: \: cm {}^{3}[/tex]

2) ≈ 395,84 м³

r = 12 ÷ 2 = 6 м

[tex]s = 6 \times 21\pi = 126\pi = 395.84... \: \: m {}^{3} [/tex]

3) ≈ 32,99 дм³

r = 4 ÷ 2 = 2 дм

[tex]s = 2 \times 5 \frac{1}{4} \pi = \frac{2 \times 21}{4} \pi = \frac{21}{2} \pi = \\ 10.5\pi = 32.99... \: \: dm {}^{3}[/tex]

4) ≈ 4,95 м³

[tex]s = \frac{3}{4} \times 2 \frac{1}{10} \pi = 0.75 \times 2.1\pi = \\ 1.575\pi = 4.95... \: \: m {}^{3} [/tex]