Răspuns:
Explicație pas cu pas:
[tex]\displaystyle L cerc = 2\pi \times r[/tex]
a) r = 10
[tex]\displaystyle L cerc = 2\pi \times r = 2\pi \times 10 = 20\pi[/tex]
b)
[tex]\displaystyle r = 6 \frac{2}{5} = \frac{6 \times 5+2}{5} = \frac{32}{5}[/tex]
[tex]\displaystyle L cerc = 2 \pi \times r = 2 \pi \times \frac{32}{5} =\frac{64}{5} \pi =12,8 \pi[/tex]
c)
[tex]\displaystyle r = 2,( 3) = 2 \frac{3}{9} = \frac{2 \times9 +3}{9} = \frac{21}{9} ^{(3} =\frac{7}{3}[/tex]
[tex]\displaystyle L cerc= 2 \pi \times r = 2 \pi \times \frac{7}{3} = \frac{14}{3} \pi = 4,(6) \pi[/tex]
d)
[tex]\displaystyle r = \frac{2}{\pi }[/tex]
[tex]\displaystyle L cerc= 2\pi \times r = 2 \pi \times \frac{2}{\pi } = \frac{4\pi }{\pi } ^{(\pi } = 4[/tex]
