CÓ +)d'//d''\Rightarrow \widehat{E_{1}}=\widehat{C}=60^o(2 góc so le trong)+)d'//d''\Rightarrow \widehat{G_{2}}=\widehat{D}=110^o(2 góc đồng vị)+)\widehat{G_{3}}+\widehat{G_{2}}=180^o(2 góc kề nhau)$\Leftrightarrow \widehat{G_{3}}=180^o-\widehat{G_{2}}=180^o-110^o=50^o+)\widehat{D_{4}}=110^o(2 góc đối đỉnh)+)\widehat{ACD}=\widehat{C}=60^o(2 góc đối đỉnh)d//d'\Rightarrow \widehat{A_{5}}=\widehat{ACD}=60^o(2 góc so le trong)+)d//d''\Rightarrow \widehat{B_{6}}=\widehat{G_{3}}=50^o$
CÓ +)
d'//d''\Rightarrow \widehat{E_{1}}=\widehat{C}=60^o(2 góc so le trong)+)
d'//d''\Rightarrow \widehat{G_{2}}=\widehat{D}=110^o(2 góc đồng vị)+)
\widehat{G_{3}}+\widehat{G_{2}}=180^o(2 góc kề nhau)$\Leftrightarrow \widehat{G_{3}}=180^o-\widehat{G_{2}}=180^o-110^o=
70^o
+)\widehat{D_{4}}=110^o
(2 góc đối đỉnh)+)\widehat{ACD}=\widehat{C}=60^o
(2 góc đối đỉnh)d//d'\Rightarrow \widehat{A_{5}}=\widehat{ACD}=60^o
(2 góc so le trong)+)d//d''\Rightarrow \widehat{B_{6}}=\widehat{G_{3}}=
70^o$