Răspuns: [tex]\bf Perimetrul_{ABCD}= 26~cm[/tex]
Explicație pas cu pas:
Salutare!
Trapezul isoscel ABCD
[tex]\bf AB = CD = 4~cm[/tex]
[tex]\bf AD - baza~mica[/tex]
[tex]\bf BC - baza~mare[/tex]
[tex]\bf AD = 8\:cm \: (baza \: mica)[/tex]
[tex]\bf AD = \dfrac{4}{5}\cdot BC = 8~cm[/tex]
[tex]\bf \dfrac{4}{5}\cdot BC = 8~cm\:\Big|\cdot 5\implies 4\cdot BC=40\:\Big|:5\implies\boxed{\bf BC=10\:cm}[/tex]
[tex]\bf Perimetrul_{ABCD}= AB+BC+CD+AD[/tex]
[tex]\bf Perimetrul_{ABCD}= 4\:cm+10\:cm+4\:cm+8\:cm[/tex]
[tex]\boxed{ \boxed {\bf Perimetrul_{ABCD}= 26~cm}}[/tex]
Varianta c) 26 cm
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