Bạn tham khảo:
$\widehat{A_{1}}=\widehat{B_{3}}$ ($2$ góc đồng vị).
$\widehat{A_{2}}=\widehat{B_{2}}$ ($2$ góc đồng vị).
$\widehat{A_{4}}+\widehat{B_{3}}=180^\circ$ ($2$ góc trong cùng phía bù nhau).
$\widehat{A_{3}}+\widehat{B_{2}}=180^\circ$ ($2$ góc trong cùng phía bù nhau).
$\widehat{A_{4}}=\widehat{B_{2}}$ ($2$ góc so le trong).
$\widehat{A_{3}}=\widehat{B_{3}}$ ($2$ góc so le trong).