Vì \(\widehat{xOy}\) và \(\widehat{yOz}\) là 2 góc kề bù
=> \(\widehat{xOy}+\widehat{yOz}=180^o\Rightarrow\widehat{yOz}=180^o-\widehat{xOy}=180^o-110^o=70^o\)
Vì \(\widehat{xOt}+\widehat{tOy}=110^o\Rightarrow\widehat{tOy}=110^o-\widehat{xOt}=110^o-40^o=70^o\)
Ta thấy \(\widehat{tOy}=\widehat{yOz}=70^o\) => Oy là phân giác góc zOt
a) Ta có: \(\widehat{xOy}+\widehat{yOz}=180^0\)(hai góc kề bù)
\(\Leftrightarrow\widehat{yOz}+110^0=180^0\)
hay \(\widehat{yOz}=70^0\)
Vậy: \(\widehat{yOz}=70^0\)