图象法令y1=√（4-x^2）则它的图象是圆x^2+y^2=4的上半圆弧.又令y2=k(x-2)+3则它的图象是恒过点(2,3)的直线(系).问题转化为当y1与y2有两个交点时,求k的取值范围.①当y2到原点的距离等于2时,k=5/12,y2与圆弧相切.②y2...