题库网
#3df168cb-0277-4f8a-bca2-466b806f5543中等fill_compute直线与圆的位置关系直线与圆+圆锥曲线

21.已知直线l1:tx+y+t+1=0l_{1}:tx+y+t+1=0与直线l2:xty+t1=0l_{2}:x-ty+t-1=0相交于点PP,动点AABB在圆C:x2+y214x+2y+47=0C:x^{2}+y^{2}-14x+2y+47=0上,且AB=2\vert AB\vert =2,则PA+PB\vert \overrightarrow{PA}+\overrightarrow{PB}\vert的取值范围是 ___[62,142][6\sqrt{2},14\sqrt{2}]___.