Răspuns:
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Explicație pas cu pas:
ΔABC≈ΔDEF AB=4 cm BC=5 cm EF=7,5 cm DF=9 cm,
AB/DE=BC/EF=AC/DF
BC/EF=AC/DF=5/7,5=AC/9 AC=5x9/7,5=6 cm
AB/DE=AC/DF 4/DE=6/9 DE=4x9/6=6 cm
