Răspuns:
MN || BC
ΔAMN¬ ΔABC
T.F.A.
⇒ [tex]\frac{AM}{AB} =\frac{AN}{AC} =\frac{MN}{BC}[/tex]
⇒[tex]\frac{4}{12} =\frac{AN}{AC} =\frac{MN}{BC}[/tex]
Cum AC =AN+NC ⇒AN =AC-NC
[tex]\frac{4}{12} =\frac{AC-NC}{AC}[/tex]⇒[tex]\frac{4}{12} =\frac{AC-6}{6}[/tex]⇒12(AC-6)=4*6⇒12(AC-6)=24⇒AC-6=2⇒AC=8cm punctul a)
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