Răspuns:
Explicație pas cu pas:
P = 2 x (L + l)
L + l = P : 2
A = L x l
a) L + l = 32 : 2 = 16 cm
l ___
L ___ ___ ___ ___ ___ ___ ___
Total = 8 parti egale = 16
1 parte = 16 : 8 = 2
l = 2 cm
L = 2 x 7 = 14 cm
A = 14 x 2 = 28 cm^2
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b)
L + l = 72 : 2 = 36
l ___
L ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___
Total 12 parti egale = 36
1 parte = 36 : 12 = 3
l = 3 cm
L = 3 x 11 = 33 cm
A = 33 x 3 = 99 cm^2
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c)
L + l = 120 : 2 = 60 cm
l = 3L/7
L + 3L/7 = 10L/7 = 60 cm
L = 60 x 7 : 10 = 42 cm
l = 42 x 3 : 7 = 18 cm
A = 42 x 18 = 756 cm^2
