弦长l>=2√3r=2则弦旦碧心距哗肆d<=√[r²-(l/2)²]=1直线kx-y+3=0则乱迟轿|3k-2+3|/√(k²+1)<=19k²-6k+1<=k²+1k(4k-3)<=00<=k<=3/4