任意五点决定的二次曲线的类型判别

DISTINGUISHING OF DIFFERENT TYPES OF THE CONIC SECTION MADE BY ANY FIVE POINTS

在射影几何中，二次曲线定理告诉我们任意五点可以决定一条二次曲线．该曲线上其它点可以用巴斯加定理求出．但是巴斯加定理只能决定该曲线上各点的位置，而不能决定其类型．本文重点解决了任意五点决定的二次曲线的类型的判别．

According to the fUndamental theorem of coniC In projective geometry any five points can decide one conic section.The other points which are belonged to this conic section can be extracted from Pascal theorem. But Pascal theorem can only deCide the poition of each point,it can not decide the type of the section. the poper solves the problem of how to distinguish different types of the conic section made by any five points.