1/(AB)^2+1/(AC)^2=[(AB)^2+(AC)^2]/[(AB)^2(AC)^2]=(BC)^2/(4S△^2)=(BC)^2/[(BC)^2(AD)^2]=1/(AD)^2
1/(AE)^2=1/(AB)^2+1/(AC)^2+1/(AD)^2,作AF⊥BC于F,上个结论1/(AB)^2+1/(AC)^2=1/(AF)^2字数不够用,联系我
1/(AB)^2+1/(AC)^2=[(AB)^2+(AC)^2]/[(AB)^2(AC)^2]=(BC)^2/(4S△^2)=(BC)^2/[(BC)^2(AD)^2]=1/(AD)^2
1/(AE)^2=1/(AB)^2+1/(AC)^2+1/(AD)^2,作AF⊥BC于F,上个结论1/(AB)^2+1/(AC)^2=1/(AF)^2字数不够用,联系我