Cho xOy = 50 do. Lay diem A tren tia Ox , ve tia At sao cho xAt = 50 do ( tia At nam trong goc xOy).

a) chung to tia At song song voi tia Oy ?

b) Ve AH vuong goc voi tia Oy ( H thuoc Oy) . Chung to AH vuong goc At.

c) Tinh so do OAH.

Cho goc xOy tu, o ben ngoai goc do ve tia Om vuong goc voi tia Ox va tia On vuong goc voi tia Oy. Chung minh rang : xOy + mOn = 180 do.

Cho hinh ve sau,biet a//b va A1 - A2 = 70 do. Tinh so do cac goc B1 va B2.

Hai duong thang MN va PQ cat nhau tai A tao thanh goc MAP .

a) tinh so do goc NAQ va goc MAQ.

b) viet ten cac cap goc doi dinh ( khac goc bet).

Cho hinh ve sau, biet Ax//Cy. Chung to rang BAx + BCy = ABC.