当直线l与圆相切时,设此时直线的斜率为k,那么y=k(x-4)代入x²+y²=8得,x²+k²(x²-8x+16)=8,整理得：(1+k²)x²-8k²x+16k²-8=0令△=64k^4-4(1+k²)(16k²-8)=0即k&#...当直线l与圆相切时，设此时直线的斜率为k，那么y=k(x-4)代入x²+y²=8得，x²+k²(x²-8x+16)=8，整理得：(1+k²)x²-8k²x+16k²-8=0令△=64k^4-4(1+k²)(16k²-8)=0即k²-1=0解得k=1或-1故倾斜角取值范围：[135°，180°)U[0,45°]