tren cung mot nua mat phang co bo chu a tia ox ve cac tia oy,om,on sao cho goc xoy = 50 do , goc xom =90 do ,xon = 130 do
a, tinh so do goc yom , so do goc mon va neu nhan xet
b, ve tia ot la tia phan giac cua goc xoy roi tinh goc mot
ngu toan dung nem gach