Α = 144·pi = pi·r^2----> r^2 = 144
quindi: r = 12 cm
Σ = area segmento circolare =144·pi·(90/360) - 1/2·r^2·SIN(90°)
Σ = (36·pi - 72) cm^2----> Σ = 41.097 cm^2
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Raggio del cerchio $r= \sqrt{\dfrac{A}{\pi}} = \sqrt{\dfrac{144\cancel{\pi}}{\cancel{\pi}}} = \sqrt{144}=12\,cm;$
area del segmento circolare:
$A_{s}= \dfrac{r^2·\pi·\alpha}{360°}-\dfrac{r^2·sen(\alpha)}{2}$
$A_{s}= \dfrac{12^2·\pi·90°}{360°}-\dfrac{12^2·sen(90°)}{2}$
$A_{s}= \dfrac{144·3,14·90}{360}-\dfrac{144·1}{2}$
$A_{s}= \dfrac{144·3,14·\cancel{90}^1}{\cancel{360}_4}-\dfrac{144}{2}$
$A_{s}= \dfrac{144·3,14}{4}-72$
$A_{s}= \dfrac{\cancel{144}^{36}·3,14}{\cancel4_1}-72$
$A_{s}= 36·3,14-72$
$A_{s}= 113,04-72 = 41,04\,cm^2.$