设半径为r,角P=45°,sqrt(n)指对n开根号,/指除号,乘号省略
=>PA=OA=r,
=>OP=sqrt(2)r,
OB=OC=r,
1)PBPB=OP-OB=[sqrt(2)-1]r,PA=[sqrt(2)+1]r
=>m=PB/PA=[sqrt(2)-1]/[sqrt(2)+1]=3-2sqrt(2)
2)PB>PC时,=>PA=OP-OA=[sqrt(2)-1]r,PB=[sqrt(2)+1]r
=>m=PB/PA=[sqrt(2)+1]/[sqrt(2)-1]=3+2sqrt(2)