Question

( Trình bày cách giải )

Answer 1

Answer 2

\(\widehat{A1}+\widehat{A4}=180\)

\(\Rightarrow\)\(\widehat{A1}=180-\widehat{A4}\)

\(\Rightarrow\)\(\widehat{A1}=50\)

mà \(\widehat{A1}=\widehat{B1}(Đồng vị)\)

\(\Rightarrow\)a // b (ĐPCM)

Answer 3

ta thấy:

\(\widehat{A_1}+\widehat{A_4}=180^o\)

⇒ \(\widehat{A_1}=180^o-130^o=50^o\)

ta có:

\(\widehat{A_1}=\widehat{B_1}=50^o\)⇒ a// b (dhnb 2 đường thẳng song song)