l=144/4=36 A=60*32/2=960 2r=960/36=26,66 r=26,66/2=13,33
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Raggio della circonferenza inscritta = apotema $\small r=\dfrac{D·d}{2p} = \dfrac{60×32}{144} = 13,\overline3\,cm\; (\approx{13,33}\,cm).$