Obwód prostokąta: Ob = 2(a + b)
[tex]a)\\a = 14 \ cm\\b = 16 cm\\\\Ob = 2(14+16) \ cm = 2\cdot30 \ cm = \boxed{60 \ cm}[/tex]
[tex]b)\\a = 3 \ cm \ \ 4 \ mm = 3,4 \ cm\\b = 5 \ cm \ \ 2 \ mm = 5,2 \ cm\\\\Ob = 2(3,4 + 5,2) \ cm = 2\cdot8,6 \ cm = \boxed{17,2 \ cm=172 \ mm}[/tex]
[tex]c)\\a = 2 \ dm = 20 \ cm\\b = 15 \ cm\\\\Ob = 2(20+15) \ cm = 2\cdot35 \ cm = \boxed{70 \ cm=7 \ dm}[/tex]
