ptts cua
CC':
\left\{ \begin{array}{l} x=t\\ y=3-2t \end{array} \right.C'\in CC'\Rightarrow C'(m;3-2m)
C' la trung diem cua AB\Rightarrow B(2m-5;4-4m)
C\in CC'\Rightarrow C(n;3-2n)\Rightarrow \overrightarrow{BC}=(n-2m+5;4m-2n-1)
goi d la duong trung truc cua BC\Rightarrow \overrightarrow{u}=(1:-1) la vecto chi phuong cua d
d vuong goc BC
\Rightarrow \overrightarrow{BC}.\overrightarrow{u}=0\Leftrightarrow n-2m+5-4m+2n+1=0\Leftrightarrow n-2m+2=0(1)
lai co:d_{(B;d)}=d_{(C;d)}\Leftrightarrow |2m-5+4-4m-6|=|n+3-6|
hay|-2m-7|=|-3-n| ( 2)
Tu (1),(2)\Rightarrow \left\{ \begin{array}{l} m=\frac{4}{3}\\ n=-6 \end{array} \right.
Vay B(-9;12),C(-6;15)