Explicație pas cu pas:
AB = AC => 2AB + BC = 30
a)
[tex]AB = AC = 12 \: cm \\ 2AB + BC = 30 \\ 2 \times 12 + BC = 30 = > BC = 6 \: cm[/tex]
b)
[tex]AC = AB = 14 \: cm \\ 2AC + BC = 30 \\ 2 \times 14 + BC = 30 = > BC = 2 \: cm[/tex]
c)
[tex]2AB + BC = 30 = > 2AB + 13 = 30 \\ 2AB = 17 = > AC = AB = 8.5 \: cm[/tex]
d)
[tex]2AB + BC = 30 = > 2AB + 11 = 30 \\ 2AB = 19 = > AC = AB = 9.5 \: cm[/tex]