a;dungphuong phap toa do: phai co toa do cu the cua A;B;CM(xM;yM) A(xA;yA) B(xB;yB)C(xC;yC)ta co:sqrt((xA-xM+xC-xB)^2+(yA-yM+yC-yB)^2)=sqrt(((xA-xM)*2/3+xB-xM)^2+((xA-xM)*2/3+xB-xM)^2)tuong duongxM^2+yM^2+2xM*TX+2yM*TY+T(A,B,C)=xM^2/9+yM^2/9+2xM*GX+2yM*GY+G(A,B)trong do, T la cac ham chua A,B,C va G la ham chua toa do cua A,B; TX la ham chua toa do x cua A,B,C, TY la ham chua toa do y cua A,B,C. G tuong tu.xM^2-xM^2/9+2xM*HX+yM^2-yM^2/9+2yM*HY+H(A;B;C)=08/9xM^2-2xM*HX+8/9yM^2-2yM*HY+H=0xM^2-2xM*HX*9/8+yM^2-2yM*HY*9/8+9/8*H=0tuong duong(xM-D)^2+(yM-E)^2=I(A;B;C)Neu I(A;B;C)<=0; khong ton tai diem M nhu vay.Neu I(A;B;C)>0: quy tich diem M la duong tron tam (D;E) ban kinh sqrt(I(A;B;C))
a;dung
phuong phap toa do: phai co toa do cu the cua
$A;B;C
$$M(xM;yM) A(xA;yA) B(xB;yB)C(xC;yC)
$ta co:
$sqrt((xA-xM+xC-xB)^2+(yA-yM+yC-yB)^2)=sqrt(((xA-xM)*2/3+xB-xM)^2+((xA-xM)*2/3+xB-xM)^2)
$tuong duong
$xM^2+yM^2+2xM*TX+2yM*TY+T(A,B,C)=xM^2/9+yM^2/9+2xM*GX+2yM*GY+G(A,B)
$trong do,
$T
$ la cac ham chua
$A,B,C
$ va
$G
$ la ham chua toa do cua
$A,B; TX
$ la ham chua toa do
$x
$ cua
$A,B,C, TY
$ la ham chua toa do
$y
$ cua
$A,B,C. G
$ tuong tu.
$xM^2-xM^2/9+2xM*HX+yM^2-yM^2/9+2yM*HY+H(A;B;C)=0
$$8/9xM^2-2xM*HX+8/9yM^2-2yM*HY+H=0
$$xM^2-2xM*HX*9/8+yM^2-2yM*HY*9/8+9/8*H=0
$tuong duong
$(xM-D)^2+(yM-E)^2=I(A;B;C)
$Neu
$I(A;B;C)<=0
$; khong ton tai diem
$M
$ nhu vay.Neu
$I(A;B;C)>0
$: quy tich diem
$M
$ la duong tron tam
$(D;E)
$ ban kinh
$sqrt(I(A;B;C))
$