Question

calculați lungimea cercului cu raza de:
a) 4cm;
b)6
_
π cm
c) 0,(4) cm;
2
d)3_ cm.
3
dau și 20 de puncte

Answer 1

$a)R = 4 \: cm$

$L=2 \pi R = 2\pi \times 4 = 8\pi$

$b)R = \frac{6}{\pi} \: cm$

$L=2\pi R = 2\pi \times \frac{6}{\pi} = 2 \times 6 = 12$

$c)R = 0.(4) = \frac{4}{9} \: cm$

$L=2\pi R = 2\pi \times \frac{4}{9} = \frac{8\pi}{9}$

$d)R = 3 \frac{2}{3} = \frac{3 \times 3 + 2}{3} = \frac{9 + 2}{3} = \frac{11}{3} \: cm$

$L=2\pi R = 2\pi \times \frac{11}{3} = \frac{22\pi}{3}$