Có: `\hat{M_2}=\hat{M_4}` (`2` góc đối đỉnh)
`=>\hat{M_4}=70^o`
Ta có: `\hat{M_1}+\hat{M_2}=180^o`
`=>\hat{M_1}+70^o =180^o`
`=>\hat{M_1}=110^o`
Vì `m //// n`
`=>{(\hat{M_2}=\hat{N_2}=\hat{N_4}=70^o),(\hat{M_1}=\hat{M_3}=\hat{N_3}=\hat{N_1}=110^o):}`
Vì `m` // `n` nên :
`=>` \(\widehat{M2}=\widehat{N2}\) ( đồng vị)
Và \(\widehat{M2}=\widehat{N4}\)( so le trong)
ta có :
\(\widehat{N3}+\widehat{N4}=180^0\)( kề bù)
`=>` \(\widehat{N3}+70^0=180^0\)
`=>`\(\widehat{N3}=180^0-70^0\)
`=>`\(\widehat{N3}=110^0\)
vậy : \(\widehat{M1}=\widehat{N3}=\widehat{M3}=\widehat{N1}=110^0\)
\(\widehat{M2}=\widehat{N4}=\widehat{N2}=70^0\)
