Question

Answer 1

a, Kẻ Bz//Ax

\(\Rightarrow\widehat{xAB}=\widehat{ABz}=20^0;\widehat{zBC}=60^0-20^0=40^0=\widehat{BCy}\)

Mà 2 góc này ở vị trí slt nên Bz//Cy

Do đó Ax//Cy

Answer 2

\(b,\widehat{ABz}=\widehat{ABC}+\widehat{CBz}=60^0+\left(90^0-\widehat{BCz}\right)=60^0+50^0=110^0\)