Cho diem O nam ngoai duong thang xy. Tren cung mot nua mat phang co bo chua duong thang xy, ke tia Oz, Ot sao cho ^zOt= 130 do, ^yOt= 100 do
a. Tia Oz la phan giac cua ^yOt khong? Vi sao?
b. Goi Om la phan giac cua ^zOt, On la tia doi cua cua Ot. Tinh so do goc mOn ?
c. Lay them 19 diem phan biet tren duong thang xy (cac diem nay khong trung voi diem O ) va mot diem A nam ngoai duong thang xy. Hoi ve duoc bao nhieu tam giac nhan 3 trong cac diem tren lam dinh.
^ la goc. giup mik voi.