15.
[tex]180^o = 3 \alpha | \div 3 \\ \alpha = 60^o[/tex]
16.
[tex]180^o - 90^o = 90^o \\ \\ 90^o \div 2 = 45^o \\ \\ \alpha = 45^o[/tex]
17.
[tex]180^o - 130^o = 50^o \\ \\ 180^o - 50^o = 130^o \\ \\ 130^o \div 2 = 65^o \\ \alpha = 65^o[/tex]
18.
Obwód prostokąta
[tex]2(76 + 66) = 2 \times 142 = 284[/tex]
Zatem bok kwadratu
[tex]4a = 284 | \div 4 \\ a = 71[/tex]
