a) a//b⇒ \(\widehat{A_4}=\widehat{B_4}=37^o\) (2 góc đồng vị)
b) \(\widehat{A_1}+\widehat{A_4}=180^o\\ \Rightarrow\widehat{A_1}++37^o=180^o\\ \Rightarrow\widehat{A_1}=143^o\)
Vì \(143^o>37^o\Rightarrow\widehat{A_1}>\widehat{B_4}\)
c) \(\widehat{B_2}=\widehat{B_4}=37^o\) (2 góc đối đỉnh)
\(\widehat{B4}=\widehat{A4}\) (đồng vị)
\(\Rightarrow\widehat{B4}=70^o\)
\(\widehat{A4}+\widehat{A1}=180^o\) ( kề bù)
\(\Rightarrow\widehat{A1}=180^o-37^o=143^o\)
\(\Rightarrow\widehat{A1}>\widehat{B4}\left(143^o>37^o\right)\)
\(\widehat{B2}=\widehat{B4}\) (đối đỉnh)
\(\Rightarrow\widehat{B2}=37^o\)
