Question

Answer 1

Xem lại ký hiệu ở hình 

Answer 2

a: Sửa đề: Ax//Dy

\(Ax\perp\)AD

Dy\(\perp\)AD

Do đó: Ax//Dy

b: Ax//Dy

=>\(\widehat{ABC}+\widehat{BCD}=180^0\)(hai góc trong cùng phía)

=>\(\widehat{ABC}+115^0=180^0\)

=>\(\widehat{ABC}=65^0\)

\(\widehat{yCB}+\widehat{DCB}=180^0\)(hai góc kề bù)

=>\(\widehat{yCB}+115^0=180^0\)

=>\(\widehat{yCB}=65^0\)

Ax//Dy

=>\(\widehat{xBC}=\widehat{BCD}\)

mà \(\widehat{BCD}=115^0\)

nên \(\widehat{xBC}=115^0\)