\(Am//Ox\Rightarrow\widehat{xOy}=\widehat{mAy}=a\)
\(\Rightarrow\widehat{OAm}=180^o-\widehat{mAy}=180^o-a\)
`#3107`
Ta có:
`\text {AM // Ox}`
`=>` \(\widehat{\text{xOA}}=\widehat{\text{A}_1}\) (2 góc đồng vị)
Mà \(\widehat{\text{A}_1}\) và \(\widehat{\text{OAm}}\) là 2 góc kề bù
`=>`\(\widehat{\text{A}_1}+\widehat{\text{OAm}}=180^0\)
`=>`\(\widehat{\text{xOA}}+\widehat{\text{OAm}}=180^0\)
`=>`\(a+\widehat{\text{ }\text{OAm}}=180^0\)
`=>`\(\widehat{\text{OAm}}=180^0-a\)
Vậy, để `\text {AM // Ox}` thì cần thỏa mãn \(\widehat{\text{OAm}}=180^0-a.\)