Question

aria unui disc de cerc este egală cu
$16\pi \: cm ^{2}$
Aflați lungimea cercului.

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Answer 1

Salut!

Răspuns:$8\pi \: cm$ ✅

$\red{aria \: = \pi {r}^{2} }$

$aria = 16\pi {cm}^{2}$

$r = \sqrt{16}$

r = 4 cm ✔

$\red{lungime = 2\pi \times r}$

$lungime = 2 \times 4 \times \pi$

$lungime = 8\pi \: cm$ ✔

Answer 2

$\it \mathcal{A}_{disc}=\pi R^2=16\pi|_{:\pi} \Rightarrow R^2=16=4^2 \Rightarrow R=4\ cm\\ \\ L_{\circ}=2\pi R=2\pi\cdot4=8\pi\ cm$