lam giup nhanh nhe'. can gap

T

tuyn

Trong khong gian voi he truc toa do Oxyz, cho cac diem A(-1,1,0) ; B( 0,0,2)
C(1,1,1). Viet' pt mat phang (P) qua 2 diem A va B dong thoi khoang cah tu C toi' mp (P) bang can 3. lam di to thnk cho:)
[TEX](P):Ax+By+Cz+D=0 (A^2+B^2+C^2 \neq 0)[/TEX]
[TEX]+A,B \in (P) \Rightarrow \left{\begin{-A+B+D=0}\\{2C+D=0} \Leftrightarrow +A,B \in (P) \Rightarrow \left{\begin{B=A+2C(1)}\\{D=-2C(2)} [/TEX]
[TEX]+d(C;(P))=\frac{|A+B+C+D|}{\sqrt{A^2+B^2+C^2}}=\sqrt{3} \Leftrightarrow |A+B+C+D|=\sqrt{3(A^2+B^2+C^2)}(3) [/TEX]
Thế (1),(2) vào (3) ta được [TEX]|2A+C|=\sqrt{3(A^2+(A+2C)^2+C^2)}[/TEX]...................
 
C

custar

cau co the dua ra dap an luon hem? vi to lam ra phuong trinh la 2x+z+2c=0 ma lai thay ko chac chan lam':D
 
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