\(\left\{{}\begin{matrix}\widehat{O_2}+\widehat{O_3}=180^0\left(kề.bù\right)\\\widehat{O_2}-\widehat{O_3}=12^0\left(kề.bù\right)\end{matrix}\right.\Rightarrow\widehat{O_2}=\left(180^0+12^0\right):2=96^0;\widehat{O_3}=84^0\)
\(\widehat{O_3}=\widehat{O_1}=84^0;\widehat{O_2}=\widehat{O_4}=96^0\left(các.cặp.góc.đối.đỉnh\right)\)