Ta có:
\(\widehat{xOy}+\widehat{x'Oy}=180^o\) (hai góc kề bù)
mà \(\widehat{x'Oy}-\widehat{xOy}=30^o\left(gt\right)\)
\(\Rightarrow\left(\widehat{xOy}+\widehat{x'Oy}\right)+\left(\widehat{x'Oy}-\widehat{xOy}\right)=180^o+30^o\)
\(\Rightarrow2\widehat{x'Oy}=210^o\Rightarrow\widehat{x'Oy}=105^o\)
\(\Rightarrow\widehat{xOy}=180^o-\widehat{x'Oy}=180^o-105^o=75^o\)
Ta lại có:
\(\left\{{}\begin{matrix}\widehat{xOy}=\widehat{x'Oy'}\\\widehat{xOy'}=\widehat{x'Oy}\end{matrix}\right.\) (đối đỉnh)
\(\Rightarrow\left\{{}\begin{matrix}\widehat{xOy}=\widehat{x'Oy'}=75^o\\\widehat{xOy'}=\widehat{x'Oy}=105^o\end{matrix}\right.\)
Chúc bạn học tốt!!!
