Ta có hình vẽ:
Ta có: góc xOy + góc xOy' = 1800 (kề bù)
Mà góc xOy = 3.góc xOy'
=> 3.góc xOy' + góc xOy' = 1800
=> 4.góc xOy' = 1800
=> góc xOy' = 1800 / 4 = 45
Ta có: góc xOy = 3.góc xOy'
=> góc xOy = 3.450 = 1350
Ta có: góc xOy = góc x'Oy' = 1350 (đđ)
Ta có: góc xOy' = góc x'Oy = 450 (đđ).
Ta có:
\(\widehat{xOy}+\widehat{xOy'}=180^o\) (1)
mà theo bài ra: \(\widehat{xOy}=3.\widehat{xOy'}\)(2)
Thay (2) vào (1) ta được:
\(3.\widehat{xOy'}+\widehat{xOy'}=180^o\Rightarrow4\widehat{xOy'}=180^o\)
\(\Rightarrow\widehat{xOy'}=45^o\)
\(\Rightarrow\widehat{xOy}=180^o-\widehat{xOy'}=180^o-45^o=135^o\)
Ta lại có:
\(\left\{{}\begin{matrix}\widehat{xOy'}=\widehat{x'Oy}\left(d.d\right)\\\widehat{xOy}=\widehat{x'Oy'}\left(d.d\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}\widehat{xOy'}=\widehat{x'Oy}=45^o\\\widehat{xOy}=\widehat{x'Oy'}=135^o\end{matrix}\right.\)
Vậy...........
Chúc bạn học tốt!!!