perim. = 2·30cm + 2 · 10cm = 80 cm
b . fig. formate ⇒ trapez drept congruente
aria AMND= ( 20 + 10 ) ·10 /2 cm² = 150 cm²
aria CNMB= ( 20 + 10 ) ·10 /2 cm² = 150 cm²
MN² = 10 ² +10² =100 +100 =200 ; MN = 10√2 = 10 · 1,41 = 14,14
9 stalpi M-------I--------I--------I--------I---------I---------I--------I--------I N
1 2 3 4 5 6 7 8 9
avem 8 segmente
1 segment = 14,14 : 8 =0,176