a) có \(\widehat{xOy}+\widehat{yOz}=180^o\left(kb\right)\)
\(hay70^o+\widehat{yOz}=180^o\)
\(\Rightarrow\widehat{yOz}=180^o-70^o\)
\(\Rightarrow\widehat{yOz}=110^o\)
b) có \(\widehat{xOy}< \widehat{xOt}\left(70^o< 120^o\right)\)
=> Oy nằm giữa hai tia Ox và Ot
\(\Rightarrow\widehat{xOy}+\widehat{yOt}=\widehat{xOt}\)
\(hay70^o+\widehat{yOt}=120^o\)
\(\Rightarrow\widehat{yOt}=120^o-70^o\)
\(\Rightarrow\widehat{yOt}=50^o\)