De on luyen DH hay lam.


 !"#$%&'()*+,-./01!"
#2!3&!"456782!39:;
 /<- 4 =/*-
 -/-   >/?-
@$$9&AB BCDE)B)
 -/FGHI5&AJ !3G
4 >/%GHI5&JKGLM
 =/@N%OJ$)P
 /%Q&ABR$QSATLM4A,)4A$)GH.
*LC%TL$LM&U1:!VHN45HLC/>'LC&D
!V* N45LC/0A(:!V)
 >/ 4 /*
 -/  =/7
W$9&A3B$
)(20cos)
23
sin(2 cmt
x
u
π
ππ
+=
X&$)
"Q:GHI&AB)L'&1B45:$%YD,./ZC
&$&AB)
 =/7 4 /W
 -/*  >/+
7[\GX]^,F.X\H)
)(100sin2100 Vtu
π

=
/
AU_`/a\bL)HGc\$&d%Q _
AU:e/f%&':[L))
 /
)(
10
,50
4
F
π
−
Ω
4 =/
)(
10
,100
4
F
π
−
Ω
 >/
)(
10.2
,100
4
F
π
−

Ω
 -/
+LC#cG!VLMG!V& gD]^,./0"Q

LC$
)L)Qc!V "Q



NW,.)g
 =/
)(210 cm
4 /
)(35 cm
 -/
)(310 cm
 >/,.
6LC)cG!V& D]-,hi^W./f"j!3k$
 =/
2
2A
L)L

l 4 /
2
A
L)L

m
 >/

2
2A
L)L

m  -/
2
A
L)L

l
<!"C'c1  !3LC9X7\LK/4\AU:b
!"$ 9Q(Ln\(C)
 /Wo 4 -/o
 >/o  =/<o
?!"\Q LC&D 
 /N%9pQ\LqN 4 >/4%1:pQN
 -/UpQ2  =/A(pQ2
rc$_G%%`G%%%Vb$4!M$X6/]+X+7/
s
*W
tX]*/
<
/uG)rG%&&B)
 -/*X7/

/ 4 =/*X7/
<
/
 /X7/
?

/  >/X7/
<
/
0Q-L)=&AT!M$v$!3GXK4AX4!M$)/
4Ae&/Q%-7X%=*7wLM4A45
 =/ 4 -/
 /  >/s
0&)XLCeQ3G(%UALC
 -/e 4 /$%&'x_
 =/45  >/$%&'M_
*%Vby21:T&1$$\y-]+

X
$$$%&'(QJ45I$\y/\_:21)g
 /X7
2
4 -/
2
 >/
3
  =/X7
WQ24!M$)!3AH$Q
 -/NWH 4 >/2AH
 /2AWH  =/2AH
7!"bC$]7y%LCy1QLd&%\LM
4%)/=\LCT%LC1X7X'1$A(7/)yk:1)
 -/4 /
 >/7  =/<
+z:LCy1QL!"y%b9dQ(C)
 =/NCX!3LC 4 /NNX!3LC

 -/NCXKLC  >/NNXKLC
6b#D{SXH!M$LC)LM4A/0RO((
L)(Q%UL)Q&c&y%& )**/_]^
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 -/X7F| 4 =/X7F|
 /X7F|  >/X7F|
<F!3)BQ1_:%%
 >/F!3)yGeL:F& 4 -/F!3%b%%
 =/F!3y}  /F!3y
?~b)T&!1:BGB4!3B
 -/$K4AU%G%&/
4 >/$K4AG%&9KU/
 /$KHG%&9KU/
 =/$KHU%G%&/
[\GX[e!3X\H)]
2120
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 =/<<` 4 -/W`
 /?+`  >/WW`
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 -/X7  =/7
FQ%u
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&K N%Ou
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 -/6 4 =/+
 /*+  >/7W
*0&1%%Vb:•B!3N%OLB%
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L)$4ALB%;
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 >/LB  =/<LB
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 =/!VHv  >/!VG{
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60&%% _X!3T&!)b%%)
 >/0H%% 4 =/ZC%%
 -/!"%%  /=A:$%%
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 =/` 4 -/7`  >/7`  /`
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 >/•%_14 -/@N2BDA&_
 /$%U„  =/)G%y_
*=QS1:U&$y]…
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 =/X+7/
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 / 4 -/  >/  =/X
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7X7/%$QUGN:LC%%N
 /7X7\LK 4 =/7X7\77
 -/X77\LK  >/77\LK
*70&X\O4NUL)1:U4\A)KH
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 /KG 4 =/G^  -/!3G  >/G^W
*+TLC%&N9‡\‡&!M!VHq N:LCy!V)
 /NNXKXxVLC
4 -/NCXKXMVLC
 =/NNXKXMVLC

 >/NCX!3XMVLC
*6[\G$1N%XOA%%\NH
# \C)B)
 >/_AU2\(&vN
4 /GO\HNL)\HN
 -/0e&dNX$2
 =/GO\HUL)\HN
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2
nR
 -/
n
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4 =/F%:(N%UALC
 -/=A(H)%UALC

 >/0H(H)%UALC
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‹ 42

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‹ !‹ ‹ X!V‹ A
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‹ 42
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‹ 42
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‹ 42
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•–/// •–/// *•–4/// W•–/// 7•–/// +•–4/// 6•–4/// <•–4///
?•–/// •–///
•–/// •–/// *•–/// W•–4/// 7•–/// +•–/// 6•–/// <•–///
?•–/// *•–///
*•–4/// *•–/// **•–/// *W•–/// *7•–/// *+•–/// *6•–4/// *<•–///
*?•–/// W•–///
W•–/// W•–/// W*•–/// WW•–4/// W7•–/// W+•–/// W6•–/// W<•–///
W?•–/// 7•–4///
”-—c&@c˜-—c&uccs=4cc4™Gs&uc&g

 !"#$%&'()*+,-./01!"
#2!3&!"456782!39:;

 /<- 4 =/*-
 -/-   >/?-
@$$9&AB BCDE)B)
 -/FGHI5&AJ !3G
4 >/%GHI5&JKGLM
 =/@N%OJ$)P
 /%Q&ABR$QSATLM4A,)4A$)GH.
*LC%TL$LM&U1:!VHN45HLC/>'LC&D
!V* N45LC/0A(:!V)
 >/ 4 /*
 -/  =/7
W$9&A3B$
)(20cos)
23
sin(2 cmt
x
u
π
ππ
+=
X&$)
"Q:GHI&AB)L'&1B45:$%YD,./ZC
&$&AB)
 =/7 4 /W
 -/*  >/+
7[\GX]^,F.X\H)
)(100sin2100 Vtu
π
=
/

AU_`/a\bL)HGc\$&d%Q _
AU:e/f%&':[L))
 /
)(
10
,50
4
F
π
−
Ω
4 =/
)(
10
,100
4
F
π
−
Ω
 >/
)(
10.2
,100
4
F
π
−
Ω
 -/

+LC#cG!VLMG!V& gD]^,./0"Q

LC$
)L)Qc!V "Q



NW,.)g
 =/
)(210 cm
4 /
)(35 cm
 -/
)(310 cm
 >/,.
6LC)cG!V& D]-,hi^W./f"j!3k$
 =/
2
2A
L)L

l 4 /
2
A
L)L

m
 >/
2
2A

L)L

m -/
2
A
L)L

l
<!"C'c1  !3LC9X7\LK/4\AU:b
!"$ 9Q(Ln\(C)
 /Wo 4 -/o
 >/o  =/<o
?!"\Q LC&D 
 /N%9pQ\LqN 4 >/4%1:p
QN
 -/UpQ2  =/A(pQ2
rc$_G%%`G%%%Vb$4!M$X6/]+X+7/
s
*W
tX]*/
<
/uG)rG%&&B)
 -/*X7/

/ 4 =/*X7/
<
/
 /X7/
?
/  >/X7/

<
/
0Q-L)=&AT!M$v$!3GXK4AX4!M$)/
4Ae&/Q%-7X%=*7wLM4A45
 =/ 4 -/