e) L = 0,2 dam = 200 cm l = 25% din L 25% din 200 cm 25 x 200 : 100 l = 50 cm P = 2 x (200 + 50) P = 500 cm
f) L = 1.5 m = 150 cm l = 1/3 din L 1/3 din 150 150 : 3 l = 50 cm P = 2 x(150+50) P = 400 cm
6 a) P = 22.32 dm = 2232 mm l = 50% din L adica L = 2l P = l + l + 2 l + 2 l P = 6 l l = 2232 : 6 l = 372 mm L = 372 x 2 L = 744 mm
b) P = 6.4 dam = 64 m L = 12 + l P = l + l + 12 l +12 l P = 4 l + 24 4 l + 24 = 64 4 l = 64 - 24 4 l = 40 l = 40 : 10 l = 10 m L = 10 + 12 L = 22 m
c) P = 12.5 dm = 125 cm = 1250 mm l = L - 12.5 cm L - 125 mm P = l + l + l - 125 + l - 125 P = 4 l - 250 4 l - 250 = 1250 4l = 1250 - 250 4 l = 1000 l = 1000 : 4 l = 250 mm L = 250 + 125 L = 375 mm
d) Semiperimetru = 3hm L = 2 x l Semiperimetru = L + l adica 2 x l + l adica 3 l l = 3 : 3 l = 1 hm L = 2 x 1 L = 2 hm