help me
1.
Ta có \(\widehat{xOy}=\widehat{x'Oy'}=65^0\left(đối.đỉnh\right)\)
Ta có \(\widehat{xOy}+\widehat{xOy'}=180^0\left(kề.bù\right)\Rightarrow\widehat{xOy'}=180^0-65^0=115^0\)
Ta có \(\widehat{xOy'}=\widehat{x'Oy}=115^0\left(đối.đỉnh\right)\)
2.
a, Ta có \(\widehat{A_2}=\widehat{A_1}=52^0\left(đối.đỉnh\right)\)
Vì a//b nên \(\widehat{A_1}=\widehat{B_2}=52^0\left(so.le.trong\right)\)
Ta có \(\widehat{B_2}+\widehat{B_1}=180^0\left(kề.bù\right)\Rightarrow\widehat{B_1}=180^0-52^0=128^0\)
Ta có \(\widehat{B_1}=\widehat{B_3}=128^0\left(đối.đỉnh\right)\)
3.
Kẻ Oa//m//n
\(\Rightarrow\widehat{mMO}=\widehat{aOM}=35^0;\widehat{nNO}=\widehat{aON}=45^0\left(so.le.trong\right)\)
\(\Rightarrow\widehat{MON}=\widehat{mMO}+\widehat{nNO}=45^0+35^0=80^0\)
