A.(4,6)
B.
D.
2 The equation of a known circle is x2+y2+ax+2y+a2=0, and the fixed point is a (1, 2). To make the crossing point A (1, 2) become two tangents of a circle, find the value range of A. 。
3. (Beijing Spring 2005 1 1) If the circle is X2+Y2+MX-
=0 is tangent to the straight line Y =- 1 and its center is on the left side of the y axis, then the value of m is _ _ _ _ _ _ _ _.