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Base del romboide (parallelogramma) $b= 3,6\,dam\;→\; = 3,6×10 = 36\,m;$
altezza $h= \dfrac{2}{3}×36 = 24\,m;$
area del terreno $A= b·h = 36×24 = 864\,m^2.$
Area A = 3,6^2*2/3 = 8,640 dam^2 = 864 m^2