Ta có: \(\widehat{xOy}=\dfrac{1}{2}\widehat{yOz}\)
nên \(\widehat{yOz}=2\cdot\widehat{xOy}\)
Ta có: \(\widehat{xOy}+\widehat{yOz}=180^0\)(hai góc kề bù)
\(\Leftrightarrow2\cdot\widehat{xOy}+\widehat{xOy}=180^0\)
\(\Leftrightarrow3\cdot\widehat{xOy}=180^0\)
hay \(\widehat{xOy}=60^0\)
Vậy: \(\widehat{xOy}=60^0\)