a: ta có: Ex\(\perp\)m
Fy\(\perp\)m
Do đó: Ex//Fy
Ta có: Ex//Fy
Cz//Ex
Do đó: Cz//Fy
b: Ta có: Cz//Ex
=>\(\widehat{zCE}=\widehat{xEC}\)(hai góc so le trong)
mà \(\widehat{xEC}=30^0\)
nên \(\widehat{zCE}=30^0\)
Ta có: \(\widehat{zCE}+\widehat{zCF}=\widehat{ECF}\)
=>\(\widehat{zCF}+30^0=110^0\)
=>\(\widehat{zCF}=80^0\)
Cz//Fy
=>\(\widehat{zCF}=\widehat{yFC}\)(hai góc so le trong)
mà \(\widehat{zCF}=80^0\)
nên \(\widehat{yFC}=80^0\)
c: ΔCAE vuông tại A
=>\(\widehat{ACE}+\widehat{AEC}=90^0\)
=>\(\widehat{ACE}+30^0=90^0\)
=>\(\widehat{ACE}=60^0\)
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