Question

[Bach Thi Anh Thu]

Bai 1: Tren duong thang AB lay diem O. Tren nua mat phang bo AB ve 2 tia OC va OD sao cho \(\widehat{AOC}=\widehat{BOD}=60^0\)

a, Hoi \(\widehat{AOC}\) va \(\widehat{BOD}\)co la 2 goc doi dinh khong? Vi sao?

b, Tren nua mat phang bo AB khong chua tia OD.Ve tia OE sao cho OB la tia phan giac cua \(\widehat{DOE}\). Hoi \(AOC\) va \(\widehat{BOE}\) co la 2 goc doi dinh khong? Vi sao?

Bai 2: 2 duong thang xx phay cat yy phay tai A sao cho \(\widehat{xAy}=47^0\). Tinh 3 goc con lai.

Answer 1

[Nguyễn Lê Phước Thịnh]

Bài 2: 

\(\widehat{xAy}=\widehat{x'Ay'}=47^0\)(hai góc đối đỉnh)

\(\widehat{xAy'}=180^0-\widehat{xAy}=133^0\)(hai góc kề bù)

=>\(\widehat{x'Ay}=133^0\)(hai góc đối đỉnh)