a/ $a//b \to \widehat{A_4}=\widehat{B_4}=37°$ (đồng vị)
b/ $\widehat{A_4}+\widehat{A_1}=180°$ (kề bù)
mà $\widehat{A_4}=37°$
$\to \widehat{A_1}=180°-37°=143°$
$\to \widehat{A_1}>\widehat{B_4}$ ($143°>37°$)
c/ $\widehat{B_4}$ đối đỉnh $\widehat{B_2}$
$\to \widehat{B_4}=\widehat{B_2}$
mà $\widehat{B_4}=37°$
$\to \widehat{B_2}=37°$