   !"##$"##%&  '() *+), / )012  '&         !" ≥ #$   3 13 ( ) 3 13 ( ) t L t N  = − − ⇔  = − +    % 3 13 t = − + !& 13 3 x = ± −   !'  !'  !' 3&    !" ≥ #$  "(")  !' *+&,*-./*-")#*- ./*-"0 ( 0   ' 0 0 0 S P ∆ >   ⇔ >   >  !#*-&*123*-  4 !'  5*-2#&,6$ 1,2 1 3,4 2 , x t x t = ± = ±  4 4 4 4 2 2 2 2 2 1 2 3 4 1 2 1 2 1 2 2( ) 2( ) 4 8( 1) 4( 2) 8 20 16 x x x x t t t t t t m m m m + + + = + = + − = − − − = − +  !' '()4   4 4 4 4 2 2 1 2 3 4 3 ( ) 28 8 20 16 28 2 5 3 0 1 ( ) 2 m N x x x x m m m m m L =   + + + = ⇔ − + = ⇔ − − = ⇔  = −   *762-8 !' '&  0 x ≥  !' 9 2 3 4 4 ( 3) 4 3 5 3 x x x x x x x ⇔ + + = + ⇔ + = +  !' 2 2 5 3 0 16( 3 ) 25 30 9 x x x x x + ≥  ⇔  + = + +   !' 2 3 1 5 9 18 9 0 x x x x  ≥ −  ⇔ ⇔ =   − + =   !' *762-9-*-6$( !' 3&  0 1 x x > ∨ < −  !'   2 , 0 1 x t t x = > + :7#$ 2 2 1 0 t t − + ≤  !' 5#/7&("# !' '()"  %( 2 1 1 1 x x x  = ⇔ = +  !'  *762-:7-*-6$( !' '& ;$<*7<<*72#"(<$""="8  8=8=  = !' 2 2 3 3 3 0 x y x xy y x y =  ⇔  + + + + =   !' %= 2 0 3 ( 1) 0 1 x x x x =   − = ⇔   =  *-*-">!"(>( !' %8  8=8=  =")!$*-7= 0, 0 x y ≥ ≥ 3& 8  8=8=  = ≥   9")?*-= !' *762-@*-*-6$">!"(>( !' 3& 9 [ ] [ ] 2 2 ( 1)( 1) 2 1 ( ) 4 ( 1)( 1) 4 ( 1)( 1) 2 x y xy x y x y x y + − =  ⇔ − − − = ⇔ + − = ⇔  + − = −    !' '()5  5#&*-"(>!"A8>!">8!"A>A(!"(>!"A>8!"A8>!">A( !' '& %2=*. 2 2 2 1 ( 1) a a a a  < + + < +  2 1 1 a a a a  < + + < +  !' B& 2 1 a a + + 3.#6$C72=*. 2 1 a a  + + 3.#6$C7D !' 3& EF2/7&GH2= 3 1 1 3 (1 )(1 ) 8 8 4 a b c a b c + + + + ≥ + + ; 3 1 1 3 (1 )(1 ) 8 8 4 b c a b c a + + + + ≥ + + <$ 3 1 1 3 (1 )(1 ) 8 8 4 c a b c a b + + + + ≥ + +  !' '()6  B&%; 3 1 3 3 3 3 3 3 ( ) 2 4 2 4 2 4 4 a b c abc ≥ + + − ≥ − = − = B72IJ#=3/( !' AB AD ABD AEC AE AC ∆ ∆  =  !' . ( ) AB AC AD AD DE ⇔ = +  !' '&      2 . . . . AD AB AC AD DE AB AC BD DC ⇔ = − = −  !' ;*K&$. AP b AP b PB a AB a b =  = +  ; AN c AN c NC a AC a c =  = +  !' B& . . ( )( ) APN ABC S AP AN bc S AB AC a b a c ∆ ∆ = = + + "(! ( )( ) BMP ABC S ca S b c a b ∆ ∆ = + + "<$ ( )( ) CMN ABC S ba S b c c a ∆ ∆ = + + "8 !' '()7  3&  M N P C B A      ;$"(!"!"8 ( ) 2 ( )( )( ) MNP ABC APN BMP CMN ABC ABC S S S S S abc S S a b b c c a ∆ ∆ ∆ ∆ ∆ ∆ ∆ − + + = = + + +  !'  !"#$%  &  )'8*9)0:. ;<'=2'>.- ?8   @AB(./C<-?0:.-'./@ /D E I D C B A . + ; 3 1 1 3 (1 )(1 ) 8 8 4 b c a b c a + + + + ≥ + + <$ 3 1 1 3 (1 )(1 ) 8 8 4 c a b c a b + + + + ≥ + +  !' '()6  B&%; 3 1 3 3 3 3 3 3 ( ) 2 4 2 4.   !" ≥ #$   3 13 ( ) 3 13 ( ) t L t N  = − − ⇔  = − +    % 3 13 t = − + !& 13 3 x = ± −   !'  !'  !' 3& amp;    !" ≥ #$  "(")  !' *+&,*-./*-")#*- ./*-"0 ( 0   '. −   *762-8 !' '&  0 x ≥  !' 9 2 3 4 4 ( 3) 4 3 5 3 x x x x x x x ⇔ + + = + ⇔ + = +  !' 2 2 5 3 0 16( 3 ) 25 30 9 x x x x x + ≥  ⇔  + = + +   !' 2 3 1 5 9 18 9 0 x x x x  ≥ −  ⇔