Prin teorema paralelelor neechidistante rezulta ca:
[tex] \frac{AE}{ED}= \frac{BF}{FC} [/tex]⇒[tex] \frac{BF}{FC}= \frac{3}{4} [/tex]⇒
[tex] \frac{BF+FC}{FC}= \frac{3+4}{4} [/tex]⇒[tex] \frac{14}{FC}= \frac{7}{4} [/tex]⇒[tex]FC= \frac{14*4}{7}=8cm [/tex]
BF=BC-FC
BF=14-8
BF=6cm