CHƯƠNG III : PHƯƠNG PHÁP TỌA ĐỘ TRONG MẶT PHẲNG PHƯƠNG TRÌNH ĐƯỜNG THẲNG Bài 1:     !u = r  "   n = − r  #$%&' k = −  ( )* Bài 2: +#, '/0.#,1.'#2.'  '3,1.'#2.'     4 *5    *d x y d x y− − = − + = 67 (*  '3,1.'#2.'    4  *5 4  *d x y d x y− + = − + = 67 %3.'%3.'68,1.'#2.'   *d x y− + =  '3,1.'#2.'     4 *5    *d x y d x y− + = − − = 67 69.''68,1.'#2.'   :  *d x y− − =  ;(67<368/=#37.#' * !*  Bài 3 +#, '/0.#,1.'#2.'d>d?@Ox5Oy<A5B/3.'A/,1.' #B+%  4 M C7/.'AB > OAB ∆ 69.'D.67d   N −   OAB S ∆ = 67d    M    ÷     ! OAB S ∆ = 67d69.''68,1.'#2.' E   *d x y− + = Bài 4:#3 ABC ∆ >(45)5 +#, '/0.#F.'@  )<.#'@()  ;,1.'#2.'(67%3.'%3.'<.#)  /.'G.(67,1.'3(H0IJ#D.,1.'3H  ;,1.'/.'/K<.#) 4 ;,1.'/.'>0.#%3.'%3.'<.#() ! ;,1.'+#D.'@/3.''( Bài 5:#3    *  d x y M− + =  0IJ#0.##HCL.  0IJ"&MN.'  +#, '/0.#,1.'#2.' d ′ &MN.' d  M  Bài 6:OP6Q/R, '&@S+,1.'#2.'%670'3#T.' .  + + = + − = 1 2 : 2 3 1 0 & : 4 5 6 0d x y d x y > − + = − + + = 3 4 : 4 2 0 & : 8 2 1 0d x y d x y   = + − − =  = − +  5 6 5 : & : 2 11 0 3 2 x t d d x y y t   = + + − =  = −  7 8 5 : & : 5 0 1 x t d d x y y  U = + − = 9 10 : 2 & : 2 4 0d x d x y Bài 7: #3#,1.'#2.'       : *5      * D x y D x my+ + = + − =  0m   D ?   D 5     V V D D 5      D D⊥ Bài 8:/3.'+IJ#3 ABC∆ >(5) 5*  R.# ABC S ∆   0IJ#J,1.'#2.'x-2y-1=0%3#3 4 ABC S ∆ = Bài 9:#3,1.'#2.'   *x y∆ − − =   W *x y ′ ∆ − + =  0/L.XM@# ∆ JY#3Z.'>[.'  R.#Y#3Z.'@#'\ ∆ 67 ′ ∆ Bài 10:#3    *x y∆ + + =    ! *x y∆ − + =  R.#''\  ∆ 67  ∆  +#, '/0.#,1.'#2.'(67#B+68  ∆ ' * !*   +#, '/0.#,1.'#2.'%3.'%3.'68  ∆ 67Y#3Z.'@#.  ∆  >[.' Bài 11:/3.'+IJ#3(5)5   +#, '/0.#,1.'#2.'(67@#])67  +#, '/0.#,1.'#2.' ∆ )67Y#3Z.'@#^. ∆ >[.' Bài 120_+#B+@@#],1.'#2.'     ! *x y∆ − + =     *x y∆ − − =    ! *x y∆ + + =  4 * *x∆ − = +#D.'@'<3>`  ∆ 67 ∆  Bài 13:#3#,1.'#2.' : 3 2 1 0x y∆ + − = 67 : 5 3 +2=0d x y−  OP6Q/R, '&'\#,1.'#2.'/L.  R.#Y#3Z.'@#^(4 .,1.'#2.' ∆  +#, '/0.#@,1.'+#D.'@'<3>`#,1.'#2.'/L.  0#J ∆ %3#3Y#3Z.'@#^.  >[.'4 4 0"#J,1.'#2.' 1 ( ) : 2 0x y∆ − = %3#3Y#3Z.'@#^". ∆ >[.'#Ca.Y#3Z.'@#^".   Bài 14  #3  #0.#  >0.#  #7.# ABCD   D  4I  67  #  <.#  .[  /L.    ! *x y∆ + − =  67     4  *x y∆ − − = +#, '/0.#@<.#b.C<#0.# >0.##7.# . 0 3 2 x t d d x y y t   = + + − =  = −  7 8 5 : & : 5 0 1 x t d d x y y  U = + − = 9 10 : 2 & : 2 4 0d x d x y Bài 7: #3#,1.'#2.'       : *5      *. 0/L.XM@# ∆ JY#3Z.'>[.'  R.#Y#3Z.'@#' ∆ 67 ′ ∆ Bài 10: #3    *x y∆ + + =    ! *x y∆ − + =  R.#''  ∆ 67  ∆  +#,