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duong thang d cach deu A,B thi d thuoc mat phang trung truc cua AB.Do d thoc (P) →d∈(P)⋂(Q) Goi trung diem I(3/2,5/2,1)cua AB;→BA(3,1,0)⇒mat phang trung truc cua AB la:(Q):3x+y−7=0 co VTPT →n(3,1,0) (P) co VTPT →u(1,1,1) ⇒→d=[→n×→u]⇒ta viet dc duong thang d co VTCP la→dva di qua diem H(2,1,4) la diem chung cua 2 mat phang (Q) va(P)
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Trả lời 11-12-12 09:42 PM
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