Question
If figure, if $AB\ ||\ CD$ and $CD\ ||\ EF$, find $\angle\text{ACE}.$
✓
Answer
Since $EF\ ||\ CD$
Therefore, $EFC + ECD = 180$ [Co-interior angles are supplementary]
$\Rightarrow ECD = 180 - 130 = 50$
Also $BA\ ||\ CD$
$\Rightarrow BAC = ACD = 70$ [alternative angles] But,
$ACE + ECD = 70 $
$\Rightarrow ACE = 70 - 50 = 20$
Therefore, $EFC + ECD = 180$ [Co-interior angles are supplementary]
$\Rightarrow ECD = 180 - 130 = 50$
Also $BA\ ||\ CD$
$\Rightarrow BAC = ACD = 70$ [alternative angles] But,
$ACE + ECD = 70 $
$\Rightarrow ACE = 70 - 50 = 20$
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