Răspunsuri

2014-08-10T11:03:13+03:00
Construim MN \perp BC.
Folosind proportii derivate din  \frac{BD}{DC} = \frac{3}{4} => \frac{BD}{BC} =\frac{3}{4+3} =\frac{3}{7} .
 \frac{A_{BMD}}{A_{ABC}} = \frac{MN \cdot BD/2}{AD \cdot BC/2} = \frac{MN \cdot BD}{2MN \cdot BC} =\\
= \frac{1}{2} \cdot  \frac{BD}{BC}= \frac{1}{2} \cdot  \frac{3}{7} = \frac{3}{14} 

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