直线与二次曲线相交所得的弦,可把它简称为相交弦。解析几何中常常碰到计算相交弦长的问题,可以不必先求出交点,再计算两点间的距离,而利用韦达定理直接导出一个计算相交弦长的公式,用起来较为方便。 The resulting string of straight lines and quadratic curves can be referred to as intersecting strings. In analytical geometry, the problem of calculating the intersecting chord length is often encountered. It is not necessary to calculate the intersection point first, and then calculate the distance between the two points, and use Veita theorem to directly derive a formula for calculating the intersecting chord length, which is more convenient to use.