圆的一般式方程C:x2+y2+Dx+Ey+F=0(D2+E2-4F>0).当点P(x0,y0)不在圆C上时,x20+y20+Dx0+Ey0+F≠0,该数值有何几何意义呢?经过探索,我们发现结论已知圆C:x2+y2+Dx+Ey+F=0(D2+E2-4F>0),点P(x0,y0).(1)点当P在圆外时,切线PA切圆于点A,则切线长 The general equation of the circle C x2 + y2 + Dx + Ey + F = 0 (D2 + E2-4F> 0) When the point P (x0, y0) is not on the circle C, x20 + y20 + Dx0 + Ey0 + F ≠ 0, what is the geometric meaning of the value? After exploration, we find that the conclusion is that the circle C: x2 + y2 + Dx + Ey + F = 0 (D2 + E2-4F> 0) (1) Point When P is outside the circle, tangent PA tangent is at point A, the tangent length is long