Ta có: \(\widehat{xOy}=\widehat{x'Oy'}=50^o\)( 2 góc đối đỉnh )
Lại có: \(\widehat{xOy}+\widehat{xOy'}=180^o\)( 2 góc kề bù )
\(\Rightarrow50^o+\widehat{xOy'}=180^o\)
\(\Rightarrow\widehat{xOy'}=130^o\)
Ta có: \(\widehat{xOy'}=\widehat{yOx'}=130^o\)( 2 góc đối đỉnh )