AD=45 cm
BC=30 cm
Fie EF⊥AB
DA⊥AB
CB⊥AB⇒ EF║AD║BC
⇒
[tex]\frac{EF}{CB}=\frac{AF}{AB}=\frac{AE}{AC}(1)\\\\ \frac{AD}{CB}=\frac{DE}{EB}=\frac{AE}{EC}(2)\\\\ \frac{EF}{AD}=\frac{BF}{AB}=\frac{BE}{BD}(3)[/tex]
Din 2 avem:
[tex]\frac{AD}{CB+AD}=\frac{AE}{AE+EC}\\\\ \frac{45}{75}= \frac{AE}{AC}[/tex]
Din 1 avem:
[tex]\frac{EF}{30}=\frac{AE}{AC}[/tex]
Din cele doua ⇒
[tex]\frac{45}{75} =\frac{EF}{30} \\\\EF=\frac{30\cdot 45}{75} =18\ cm[/tex]
Raspuns: c) 18 cm
Un alt exercitiu gasesti aici: https://brainly.ro/tema/3336417
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