[tex]1. \\ p = 40 + 40 + 36 = 116 \: cm \\ p = 18 \times 4 = 72 \: cm \\ p = 2 \times 458 + 2 \times (458 + 215) = 2 \times 458 + 2 \times 673 = 916 + 1346 = 2262 \: cm \\ p= 2 \times 210 + 2 \times (2 \times 210) = 420 + 840 = 1260 \: cm[/tex]
[tex]2. \\ p = 3 \times l = 3 \times 27 = 81cm[/tex]
[tex]3. \\ p = 3 \times l = 30 \\ l = 30 \div 3 = 10 \:m[/tex]
[tex]4. \\ p = ab + bc + ca = (ab + ca) + (ab \div 2) = \\ p = 16 + (8 \div 2) = 16 + 4 = 20 \: cm[/tex]
