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2014 summer B 807 a

Date post: 29-Jun-2015
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ื. ื‘ื’ืจื•ืช ืœื‘ืชื™ ืกืคืจ ืขืœึพื™ืกื•ื“ื™ื™ื ืกื•ื’ ื”ื‘ื—ื™ื ื”: ืžื“ื™ื ืช ื™ืฉืจืืœ ื‘. ื‘ื’ืจื•ืช ืœื ื‘ื—ื ื™ื ืืงืกื˜ืจื ื™ื™ื ืžืฉืจื“ ื”ื—ื™ื ื•ืš ืžื•ืขื“ ื‘ ืชืฉืข"ื“, ืžื•ืขื“ ื”ื‘ื—ื™ื ื”:317 ,035807 : ืžืกืคืจ ื”ืฉืืœื•ืŸ ื”ืฆืขืช ืชืฉื•ื‘ื•ืช ืœืฉืืœื•ืช ื‘ื—ื™ื ืช ื”ื‘ื’ืจื•ืช ืžืชืžื˜ื™ืงื” ื™ื—ื™ื“ื•ืช ืœื™ืžื•ื“ โ€” ืฉืืœื•ืŸ ืฉื ื™5 ื”ื•ืจืื•ืช ืœื ื‘ื—ืŸ ืฉืขืชื™ื™ื. ืžืฉืš ื”ื‘ื—ื™ื ื”: ื. ื‘ืฉืืœื•ืŸ ื–ื” ืฉื ื™ ืคืจืงื™ื. ืžื‘ื ื” ื”ืฉืืœื•ืŸ ื•ืžืคืชื— ื”ื”ืขืจื›ื”: ื‘. ื’ืื•ืžื˜ืจื™ื”ืื ืœื™ื˜ื™ืช,ื•ืงื˜ื•ืจื™ื,โ€” ืคืจืง ืจืืฉื•ืŸ ื˜ืจื™ื’ื•ื ื•ืžื˜ืจื™ื” ื‘ืžืจื—ื‘, ื ืงื•ื“ื•ืช66 3 2 โ€” 33 3 1 #2 โ€” ืžืกืคืจื™ื ืžืจื•ื›ื‘ื™ื ื’ื“ื™ืœื” ื•ื“ืขื™ื›ื”, ืคื•ื ืงืฆื™ื•ืช ื—ื–ืงื”,โ€” ืฉื ื™ ืคืจืง ื ืงื•ื“ื•ืช33 3 1 โ€” 33 3 1 #1 โ€” ืคื•ื ืงืฆื™ื•ืช ืžืขืจื™ื›ื™ื•ืชื•ืœื•ื’ืจื™ืชืžื™ื•ืช ื ืงื•ื“ื•ืช100 โ€” ืกื”"ื›: ื—ื•ืžืจ ืขื–ืจ ืžื•ืชืจ ื‘ืฉื™ืžื•ืฉ ื’. ืžื—ืฉื‘ื•ืŸ ืœื ื’ืจืคื™. ืื™ืŸ ืœื”ืฉืชืžืฉ ื‘ืืคืฉืจื•ื™ื•ืช ื”ืชื›ื ื•ืช ื‘ืžื—ืฉื‘ื•ืŸ ื”ื ื™ืชืŸ ืœืชื›ื ื•ืช.)1( ืฉื™ืžื•ืฉ ื‘ืžื—ืฉื‘ื•ืŸ ื’ืจืคื™ ืื• ื‘ืืคืฉืจื•ื™ื•ืช ื”ืชื›ื ื•ืช ื‘ืžื—ืฉื‘ื•ืŸ ืขืœื•ืœ ืœื’ืจื•ื ืœืคืกื™ืœืช ื”ื‘ื—ื™ื ื”..)ืžืฆื•ืจืคื™ื( ื“ืคื™ ื ื•ืกื—ืื•ืช)2( : ื”ื•ืจืื•ืช ืžื™ื•ื—ื“ื•ืช ื“. ืืœ ืชืขืชื™ืง ืืช ื”ืฉืืœื”; ืกืžืŸ ืืช ืžืกืคืจื” ื‘ืœื‘ื“.)1( ื”ืชื—ืœ ื›ืœ ืฉืืœื” ื‘ืขืžื•ื“ ื—ื“ืฉ. ืจืฉื•ื ื‘ืžื—ื‘ืจืช ืืช ืฉืœื‘ื™ ื”ืคืชืจื•ืŸ, ื’ื ื›ืืฉืจ)2( ื”ื—ื™ืฉื•ื‘ื™ื ืžืชื‘ืฆืขื™ื ื‘ืขื–ืจืช ืžื—ืฉื‘ื•ืŸ. ื”ืกื‘ืจ ืืช ื›ืœ ืคืขื•ืœื•ืชื™ืš, ื›ื•ืœืœ ื—ื™ืฉื•ื‘ื™ื, ื‘ืคื™ืจื•ื˜ ื•ื‘ืฆื•ืจื” ื‘ืจื•ืจื” ื•ืžืกื•ื“ืจืช. ื—ื•ืกืจ ืคื™ืจื•ื˜ ืขืœื•ืœ ืœื’ืจื•ื ืœืคื’ื™ืขื” ื‘ืฆื™ื•ืŸ ืื• ืœืคืกื™ืœืช ื”ื‘ื—ื™ื ื”. ืœื˜ื™ื•ื˜ื” ื™ืฉ ืœื”ืฉืชืžืฉ ื‘ืžื—ื‘ืจืช ื”ื‘ื—ื™ื ื” ืื• ื‘ื“ืคื™ื ืฉืงื™ื‘ืœืช ืžื”ืžืฉื’ื™ื—ื™ื.)3( ืฉื™ืžื•ืฉ ื‘ื˜ื™ื•ื˜ื” ืื—ืจืช ืขืœื•ืœ ืœื’ืจื•ื ืœืคืกื™ืœืช ื”ื‘ื—ื™ื ื”. ื”ื”ื ื—ื™ื•ืช ื‘ืฉืืœื•ืŸ ื–ื” ืžื ื•ืกื—ื•ืช ื‘ืœืฉื•ืŸ ื–ื›ืจ ื•ืžื›ื•ื•ื ื•ืช ืœื ื‘ื—ื ื•ืช ื•ืœื ื‘ื—ื ื™ื ื›ืื—ื“. ื‘ื”ืฆืœื—ื”! /ื”ืžืฉืš ืžืขื‘ืจ ืœื“ืฃ/
Transcript
Page 1: 2014 summer B 807 a

ื. ื‘ื’ืจื•ืช ืœื‘ืชื™ ืกืคืจ ืขืœึพื™ืกื•ื“ื™ื™ื ืกื•ื’ ื”ื‘ื—ื™ื ื”: ืžื“ื™ื ืช ื™ืฉืจืืœ ื‘. ื‘ื’ืจื•ืช ืœื ื‘ื—ื ื™ื ืืงืกื˜ืจื ื™ื™ื ืžืฉืจื“ ื”ื—ื™ื ื•ืš

ืชืฉืข"ื“, ืžื•ืขื“ ื‘ ืžื•ืขื“ ื”ื‘ื—ื™ื ื”: 317 ,035807 ืžืกืคืจ ื”ืฉืืœื•ืŸ:

ื”ืฆืขืช ืชืฉื•ื‘ื•ืช ืœืฉืืœื•ืช ื‘ื—ื™ื ืช ื”ื‘ื’ืจื•ืช

ื” ืง ื™ ื˜ ืž ืช ืž5 ื™ื—ื™ื“ื•ืช ืœื™ืžื•ื“ โ€” ืฉืืœื•ืŸ ืฉื ื™

ื”ื•ืจืื•ืช ืœื ื‘ื—ืŸ

ืžืฉืš ื”ื‘ื—ื™ื ื”: ืฉืขืชื™ื™ื. ื.

ืžื‘ื ื” ื”ืฉืืœื•ืŸ ื•ืžืคืชื— ื”ื”ืขืจื›ื”: ื‘ืฉืืœื•ืŸ ื–ื” ืฉื ื™ ืคืจืงื™ื. ื‘.

ื’ืื•ืžื˜ืจื™ื” ืื ืœื™ื˜ื™ืช, ื•ืงื˜ื•ืจื™ื, โ€” ืคืจืง ืจืืฉื•ืŸ

ื˜ืจื™ื’ื•ื ื•ืžื˜ืจื™ื” ื‘ืžืจื—ื‘,

66 ื ืงื•ื“ื•ืช 32

โ€” 33 31#2 โ€” ืžืกืคืจื™ื ืžืจื•ื›ื‘ื™ื

ื’ื“ื™ืœื” ื•ื“ืขื™ื›ื”, ืคื•ื ืงืฆื™ื•ืช ื—ื–ืงื”, โ€” ืคืจืง ืฉื ื™

33 ื ืงื•ื“ื•ืช 31

โ€” 33 31#1 ืคื•ื ืงืฆื™ื•ืช ืžืขืจื™ื›ื™ื•ืช ื•ืœื•ื’ืจื™ืชืžื™ื•ืช โ€”

โ€” 100 ื ืงื•ื“ื•ืช ืกื”"ื›

ื—ื•ืžืจ ืขื–ืจ ืžื•ืชืจ ื‘ืฉื™ืžื•ืฉ: ื’.

ืžื—ืฉื‘ื•ืŸ ืœื ื’ืจืคื™. ืื™ืŸ ืœื”ืฉืชืžืฉ ื‘ืืคืฉืจื•ื™ื•ืช ื”ืชื›ื ื•ืช ื‘ืžื—ืฉื‘ื•ืŸ ื”ื ื™ืชืŸ ืœืชื›ื ื•ืช. )1(

ืฉื™ืžื•ืฉ ื‘ืžื—ืฉื‘ื•ืŸ ื’ืจืคื™ ืื• ื‘ืืคืฉืจื•ื™ื•ืช ื”ืชื›ื ื•ืช ื‘ืžื—ืฉื‘ื•ืŸ ืขืœื•ืœ ืœื’ืจื•ื ืœืคืกื™ืœืช ื”ื‘ื—ื™ื ื”.

ื“ืคื™ ื ื•ืกื—ืื•ืช )ืžืฆื•ืจืคื™ื(. )2(

ื”ื•ืจืื•ืช ืžื™ื•ื—ื“ื•ืช: ื“.

ืืœ ืชืขืชื™ืง ืืช ื”ืฉืืœื”; ืกืžืŸ ืืช ืžืกืคืจื” ื‘ืœื‘ื“. )1(

ื”ืชื—ืœ ื›ืœ ืฉืืœื” ื‘ืขืžื•ื“ ื—ื“ืฉ. ืจืฉื•ื ื‘ืžื—ื‘ืจืช ืืช ืฉืœื‘ื™ ื”ืคืชืจื•ืŸ, ื’ื ื›ืืฉืจ )2(

ื”ื—ื™ืฉื•ื‘ื™ื ืžืชื‘ืฆืขื™ื ื‘ืขื–ืจืช ืžื—ืฉื‘ื•ืŸ.

ื”ืกื‘ืจ ืืช ื›ืœ ืคืขื•ืœื•ืชื™ืš, ื›ื•ืœืœ ื—ื™ืฉื•ื‘ื™ื, ื‘ืคื™ืจื•ื˜ ื•ื‘ืฆื•ืจื” ื‘ืจื•ืจื” ื•ืžืกื•ื“ืจืช.

ื—ื•ืกืจ ืคื™ืจื•ื˜ ืขืœื•ืœ ืœื’ืจื•ื ืœืคื’ื™ืขื” ื‘ืฆื™ื•ืŸ ืื• ืœืคืกื™ืœืช ื”ื‘ื—ื™ื ื”.

ืœื˜ื™ื•ื˜ื” ื™ืฉ ืœื”ืฉืชืžืฉ ื‘ืžื—ื‘ืจืช ื”ื‘ื—ื™ื ื” ืื• ื‘ื“ืคื™ื ืฉืงื™ื‘ืœืช ืžื”ืžืฉื’ื™ื—ื™ื. )3(

ืฉื™ืžื•ืฉ ื‘ื˜ื™ื•ื˜ื” ืื—ืจืช ืขืœื•ืœ ืœื’ืจื•ื ืœืคืกื™ืœืช ื”ื‘ื—ื™ื ื”.

ื”ื”ื ื—ื™ื•ืช ื‘ืฉืืœื•ืŸ ื–ื” ืžื ื•ืกื—ื•ืช ื‘ืœืฉื•ืŸ ื–ื›ืจ ื•ืžื›ื•ื•ื ื•ืช ืœื ื‘ื—ื ื•ืช ื•ืœื ื‘ื—ื ื™ื ื›ืื—ื“.

! ื” ื— ืœ ืฆ ื” ื‘/ื”ืžืฉืš ืžืขื‘ืจ ืœื“ืฃ/

Page 2: 2014 summer B 807 a

ืชืฉื•ื‘ื•ืช, ืžืชืžื˜ื™ืงื”, ืงื™ืฅ ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317- 2 -

ืฉืืœื” 1

ืžืชืžื˜ื™ืงื”, ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317 + ื ืกืคื— - 2 -ืช ื• ืœ ื ืฉ ื”

ื”ืกื‘ืจ ืืช ื›ืœ ืคืขื•ืœื•ืชื™ืš, ื›ื•ืœืœ ื—ื™ืฉื•ื‘ื™ื, ื‘ืคื™ืจื•ื˜ ื•ื‘ืฆื•ืจื” ื‘ืจื•ืจื”. ืฉื™ื ืœื‘! ื—ื•ืกืจ ืคื™ืจื•ื˜ ืขืœื•ืœ ืœื’ืจื•ื ืœืคื’ื™ืขื” ื‘ืฆื™ื•ืŸ ืื• ืœืคืกื™ืœืช ื”ื‘ื—ื™ื ื”.

ืคืจืง ืจืืฉื•ืŸ โ€” ื’ืื•ืžื˜ืจื™ื” ืื ืœื™ื˜ื™ืช, ื•ืงื˜ื•ืจื™ื, ื˜ืจื™ื’ื•ื ื•ืžื˜ืจื™ื” ื‘ืžืจื—ื‘, 66 ื ืงื•ื“ื•ืช( 3

2 ืžืกืคืจื™ื ืžืจื•ื›ื‘ื™ื )

33 ื ืงื•ื“ื•ืช(. 31 ืขื ื” ืขืœ ืฉืชื™ื™ื ืžื”ืฉืืœื•ืช 3-1 )ืœื›ืœ ืฉืืœื” โ€”

ืฉื™ื ืœื‘! ืื ืชืขื ื” ืขืœ ื™ื•ืชืจ ืžืฉืชื™ ืฉืืœื•ืช, ื™ื™ื‘ื“ืงื• ืจืง ืฉืชื™ ื”ืชืฉื•ื‘ื•ืช ื”ืจืืฉื•ื ื•ืช ืฉื‘ืžื—ื‘ืจืชืš.

ื ืงื•ื“ื” A ื ืžืฆืืช ื‘ืจื‘ื™ืข ื”ืจืืฉื•ืŸ .1

. y x32= ืขืœ ื”ืคืจื‘ื•ืœื” ืฉืžืฉื•ื•ืืชื”

B ื™ืฉืจ ื”ืžืฉื™ืง ืœืคืจื‘ื•ืœื” ื‘ื ืงื•ื“ื”

ืžืงื‘ื™ืœ ืœืžื™ืชืจ O( OA โ€” ืจืืฉื™ืช ื”ืฆื™ืจื™ื(.

. x ื”ืขื‘ื™ืจื• ื™ืฉืจ ื”ืžืงื‘ื™ืœ ืœืฆื™ืจ ื”ึพ A ื“ืจืš ื”ื ืงื•ื“ื”

ื”ื™ืฉืจ ื—ื•ืชืš ืืช ื”ืžืฉื™ืง ื‘ื ืงื•ื“ื” C )ืจืื” ืฆื™ื•ืจ(.

. C ืฉืœ ื”ื ืงื•ื“ื” x ืฉื™ืขื•ืจ ื”ึพ โ€” xC ื ืกืžืŸ:

. A ืฉืœ ื”ื ืงื•ื“ื” x ืฉื™ืขื•ืจ ื”ึพ โ€” xA

, y x42= ื”ื™ืขื–ืจ ื‘ืขื•ื‘ื“ื” ืฉื”ื ืงื•ื“ื” C ื ืžืฆืืช ืขืœ ืคืจื‘ื•ืœื” ืฉืžืฉื•ื•ืืชื”

ื•ืขื ื” ืขืœ ื”ืกืขื™ืคื™ื ื, ื‘ ื•ึพ ื’.

. xA xC ืืช ื”ื‘ืข ื‘ืืžืฆืขื•ืช ื.

. OA ืืช ื”ืฉื™ืคื•ืข ืฉืœ ื”ื™ืฉืจ xC ื”ื‘ืข ื‘ืืžืฆืขื•ืช ื‘.

ื ืชื•ืŸ ื’ื ื›ื™ ืฉื˜ื— ื”ืžืฉื•ืœืฉ BCA ื”ื•ื 0.5625 . ื’.

. C ืžืฆื ืืช ื”ืฉื™ืขื•ืจื™ื ืฉืœ ื”ื ืงื•ื“ื”

ื”ืžืฉืš ื‘ืขืžื•ื“ 3

y

x

B

O

AC

ืชืฉื•ื‘ื” ืœืฉืืœื” 1

y yA C= CA ืžืงื‘ื™ืœ ืœืฆื™ืจ ื”ึพ x , ืœื›ืŸ: ื.

I. xy y3 3AA C2 2

= = y , ืœื›ืŸ: x32= A ืขืœ ื”ืคืจื‘ื•ืœื”

II. y x4C C2 = y , ืœื›ืŸ: x42= C ืขืœ ื”ืคืจื‘ื•ืœื”

xx34

AC= ืžึพ I ื•ึพ II ืžืงื‘ืœื™ื:

m xy

OA AA= ื”ืฉื™ืคื•ืข OA ืžืงื™ื™ื: ื‘.

0

m xy

OA AC=

0

y x4C C= x ื•ึพ x34

AC= ื ืฆื™ื‘

m xx

x43 4

23 1

OA CC

C$= = )C ื‘ืจื‘ื™ืข ื”ืจืืฉื•ืŸ(:

/ื”ืžืฉืš ื‘ืขืžื•ื“ 3/

Page 3: 2014 summer B 807 a

ืชืฉื•ื‘ื•ืช, ืžืชืžื˜ื™ืงื”, ืงื™ืฅ ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317- 3 -

ื”ืžืฉืš ืชืฉื•ื‘ื” ืœืฉืืœื” 1

( )y y x x23

B B$ = + y ื‘ื ืงื•ื“ื” B ื”ื™ื: x32= ืžืฉื•ื•ืืช ื”ืžืฉื™ืง ืœืคืจื‘ื•ืœื” ื’.

0

m y23B

= ืฉื™ืคื•ืข ื”ืžืฉื™ืง ื‘ื ืงื•ื“ื” B ื”ื•ื:

m mOA= ื”ืžืฉื™ืง ื‘ื ืงื•ื“ื” B ืžืงื‘ื™ืœ ืœืžื™ืชืจ OA , ืœื›ืŸ:

0

y x23

23 1

B C$=

0

y xB C=

. y y x x0 5625 21

C B CA= - -^ ^h h ืฉื˜ื— ื”ืžืฉื•ืœืฉ BCA ืžืงื™ื™ื:

0

. x x x x0 5625 21 4 3

4C C C C= - -_ bi l

0

. xx

x0 5625 6 61

C

C2

23

= = C

0

C32

( . ) x0 5625 6$ =

0

.x 2 25C= (2.25 , 3)C&

.y 4 2 25 3C $= =

/ื”ืžืฉืš ื‘ืขืžื•ื“ 4/

Page 4: 2014 summer B 807 a

ืชืฉื•ื‘ื•ืช, ืžืชืžื˜ื™ืงื”, ืงื™ืฅ ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317- 4 -

ืžืชืžื˜ื™ืงื”, ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317 + ื ืกืคื— ืฉืืœื” 2 - 3 -. CD ื”ื•ื AB ื’ื•ื‘ื” ื”ืžืฉื•ืœืฉ ืœืฆืœืข , ABC ื‘ืžืฉื•ืœืฉ .2

. tAD AB= , vCB= , uCA= ื ืกืžืŸ:

. CB 2= , CA 1= , cos ACB 43

B = ื ืชื•ืŸ:

ื—ืฉื‘ ืืช ื”ืขืจืš ืฉืœ t ื‘ืขื–ืจืช ื—ืฉื‘ื•ืŸ ื•ืงื˜ื•ืจื™ื. ื.

t ื›ืš ืฉื”ืกืจื˜ื•ื˜ ื™ืชืื™ื ืœืขืจืš ืฉืœ CD ื•ืืช ื”ื’ื•ื‘ื” ABC ืกืจื˜ื˜ ืืช ื”ืžืฉื•ืœืฉ ื‘.

ืฉื—ื™ืฉื‘ืช ื‘ืกืขื™ืฃ ื.

.)C ืœึพ B ื‘ื™ืŸ( BC ื ืžืฆืืช ืขืœ ื”ืฆืœืข E ื ืงื•ื“ื” ื’.

. hCD= BE . ื ืกืžืŸ: CE

53

= ื ืชื•ืŸ ื’ื:

h ื‘ืœื‘ื“. u ื•ึพ AE ื‘ืืžืฆืขื•ืช ื”ื‘ืข ืืช

z , z ื”ื•ื ืžืกืคืจ ืžืจื•ื›ื‘.z1

2 1 14

-+

=b l ืคืชื•ืจ ืืช ื”ืžืฉื•ื•ืื”: ื. .3

ื”ืื ืฉืœื•ืฉื” ืžืŸ ื”ืคืชืจื•ื ื•ืช ืฉืžืฆืืช ื‘ืกืขื™ืฃ ื ื ืžืฆืื™ื ืขืœ ื”ืžืงื•ื ื”ื’ืื•ืžื˜ืจื™ ื‘.

) ? ื ืžืง. )arg w107 253o o1 1 ืฉืœ ื”ืžืกืคืจื™ื ื”ืžืจื•ื›ื‘ื™ื w ื”ืฉื•ื ื™ื ืžึพ 0 ื•ืžืงื™ื™ืžื™ื:

ื”ืžืฉืš ื‘ืขืžื•ื“ 4

ืชืฉื•ื‘ื” ืœืฉืืœื” 2

ABtCD CA AD CA= + = + ืœืคื™ ื—ื™ื‘ื•ืจ ื•ืงื˜ื•ืจื™ื: ื.

0

( )u t v uCD= + -

CD AB 0$ = CD ืœื›ืŸ: AB=

0

( ( )) ( )u t v u v u 0$+ - - =

0

( ) ( )cos cost v t u v ACB t u v ACB t u1 1 02 2$ $ $ $ $B B+ - - - =-

0

t 41

=- cos , ื•ื ืงื‘ืœ: ACB 43

B = , v 2= , u 1= ื ืฆื™ื‘

/ื”ืžืฉืš ื‘ืขืžื•ื“ 5/

Page 5: 2014 summer B 807 a

ืชืฉื•ื‘ื•ืช, ืžืชืžื˜ื™ืงื”, ืงื™ืฅ ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317- 5 -

ื”ืžืฉืš ืชืฉื•ื‘ื” ืœืฉืืœื” 2.

AB ืžื—ื•ืฅ ืœืงื˜ืข D ืœื›ืŸ , t 41

=- ืžืฆืื ื• ื›ื™ ื‘.

AD ื‘ื›ื™ื•ื•ืŸ ื”ืคื•ืš ืœึพ AB , ืœื›ืŸ ื”ืžืฉื•ืœืฉ ื”ื•ื: ื›ืš ืฉึพ

D BA

E

C

h u

v u-

v

vCE CB83

83

= = CE , ืœื›ืŸ: BE53

= ืœืคื™ ื”ื ืชื•ืŸ ื’.

v uAE CE CA 83

= - = - ืœืคื™ ื—ื™ื‘ื•ืจ ื•ืงื˜ื•ืจื™ื:

( )v h v u v u h v uCD AD AB 41

45

45

= - + = + - + - = + - ) , ืœื›ืŸ: )v uAD 41

=- -

0

v h u4 5=- +

( )h u uAE 83 4 5= - + - AE , ื•ื ืงื‘ืœ: v ื‘ึพ ื ืฆื™ื‘ ืืช

0

u hAE 87

23

= -

/ื”ืžืฉืš ื‘ืขืžื•ื“ 6/

Page 6: 2014 summer B 807 a

ืชืฉื•ื‘ื•ืช, ืžืชืžื˜ื™ืงื”, ืงื™ืฅ ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317- 6 -

ืฉืืœื” 3

ืžืชืžื˜ื™ืงื”, ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317 + ื ืกืคื— - 3 -. CD ื”ื•ื AB ื’ื•ื‘ื” ื”ืžืฉื•ืœืฉ ืœืฆืœืข , ABC ื‘ืžืฉื•ืœืฉ .2

. tAD AB= , vCB= , uCA= ื ืกืžืŸ:

. CB 2= , CA 1= , cos ACB 43

B = ื ืชื•ืŸ:

ื—ืฉื‘ ืืช ื”ืขืจืš ืฉืœ t ื‘ืขื–ืจืช ื—ืฉื‘ื•ืŸ ื•ืงื˜ื•ืจื™ื. ื.

t ื›ืš ืฉื”ืกืจื˜ื•ื˜ ื™ืชืื™ื ืœืขืจืš ืฉืœ CD ื•ืืช ื”ื’ื•ื‘ื” ABC ืกืจื˜ื˜ ืืช ื”ืžืฉื•ืœืฉ ื‘.

ืฉื—ื™ืฉื‘ืช ื‘ืกืขื™ืฃ ื.

.)C ืœึพ B ื‘ื™ืŸ( BC ื ืžืฆืืช ืขืœ ื”ืฆืœืข E ื ืงื•ื“ื” ื’.

. hCD= BE . ื ืกืžืŸ: CE

53

= ื ืชื•ืŸ ื’ื:

h ื‘ืœื‘ื“. u ื•ึพ AE ื‘ืืžืฆืขื•ืช ื”ื‘ืข ืืช

z , z ื”ื•ื ืžืกืคืจ ืžืจื•ื›ื‘.z1

2 1 14

-+

=b l ืคืชื•ืจ ืืช ื”ืžืฉื•ื•ืื”: ื. .3

ื”ืื ืฉืœื•ืฉื” ืžืŸ ื”ืคืชืจื•ื ื•ืช ืฉืžืฆืืช ื‘ืกืขื™ืฃ ื ื ืžืฆืื™ื ืขืœ ื”ืžืงื•ื ื”ื’ืื•ืžื˜ืจื™ ื‘.

) ? ื ืžืง. )arg w107 253o o1 1 ืฉืœ ื”ืžืกืคืจื™ื ื”ืžืจื•ื›ื‘ื™ื w ื”ืฉื•ื ื™ื ืžึพ 0 ื•ืžืงื™ื™ืžื™ื:

ื”ืžืฉืš ื‘ืขืžื•ื“ 4

ืชืฉื•ื‘ื” ืœืฉืืœื” 3

, k ืฉืœื ( )zz cis k12 1 1 0 360o o4-+

= = +b l cos , ื•ื ืงื‘ืœ: sini cisa a a+ = ื ืกืžืŸ: ื.

0

( ) , , , ,zz cis k k12 1 90 0 1 2 3o-+= =

0

0 1 , 90 , 180 1 , 270zz

cis zz

cis i zz

cis zz

cis i12 1

12 1

12 1

12 1o o o o

00

11

22

33

-

+= = -

+= = -

+= =- -

+= =-

0 0 0 0

z 20=- , z i51

53

1=- - , 0z2= , z i51

53

3=- +

ื”ื–ื•ื•ื™ื•ืช, ืฉื™ื•ืฆืจื™ื ื”ืžืกืคืจื™ื z3 , z1 , z0 ื”ืฉื•ื ื™ื ืžึพ 0 ื‘.

0 , 3 , 3tg tg tg20

5153

5153

0 1 3a a a=- = =-

-= =

-=- ืขื ื”ื›ื™ื•ื•ืŸ ื”ื—ื™ื•ื‘ื™ ืฉืœ ืฆื™ืจ ื”ึพ x , ืžืงื™ื™ืžื•ืช:

0 0 0 ืœืคื™ ืฉื™ืขื•ืจื™ ื”ึพ x ื•ื”ึพ y ืฉืœ ื”ืžืกืคืจื™ื:

z1 ื‘ืจื‘ื™ืข ื”ืฉืœื™ืฉื™, z3 ื‘ืจื‘ื™ืข ื”ืฉื ื™

( ) 180arg z o0 = , ( ) 251.56arg z o

1 = , ( ) 108.43arg z o3 = z0 ื ืžืฆื ื‘ื—ืœืง ื”ืฉืœื™ืœื™ ืฉืœ ืฆื™ืจ ื”ึพ x , ืœื›ืŸ: ื•ึพ

0

z0 ืขืœ ื”ืžืงื•ื ื”ื’ืื•ืžื˜ืจื™ , z1 , z3

( )arg w107 253o o1 1 ืฉืœ ื”ืžืกืคืจื™ื ื”ืžืงื™ื™ืžื™ื

/ื”ืžืฉืš ื‘ืขืžื•ื“ 7/

Page 7: 2014 summer B 807 a

ืชืฉื•ื‘ื•ืช, ืžืชืžื˜ื™ืงื”, ืงื™ืฅ ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317- 7 -

ืฉืืœื” 4

ืžืชืžื˜ื™ืงื”, ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317 + ื ืกืคื— - 4 -

ืคืจืง ืฉื ื™ โ€” ื’ื“ื™ืœื” ื•ื“ืขื™ื›ื”, ืคื•ื ืงืฆื™ื•ืช ืžืขืจื™ื›ื™ื•ืช ื•ืœื•ื’ืจื™ืชืžื™ื•ืช33 ื ืงื•ื“ื•ืช( 3

1 (

ืขื ื” ืขืœ ืื—ืช ืžื”ืฉืืœื•ืช 5-4.

ืฉื™ื ืœื‘! ืื ืชืขื ื” ืขืœ ื™ื•ืชืจ ืžืฉืืœื” ืื—ืช, ืชื™ื‘ื“ืง ืจืง ื”ืชืฉื•ื‘ื” ื”ืจืืฉื•ื ื” ืฉื‘ืžื—ื‘ืจืชืš.

) , a ื”ื•ื ืคืจืžื˜ืจ. )( )f xex2 3ax=

- +ื ืชื•ื ื” ื”ืคื•ื ืงืฆื™ื” .4

? f(x) ืžื”ื• ืชื—ื•ื ื”ื”ื’ื“ืจื” ืฉืœ ื”ืคื•ื ืงืฆื™ื” )1( ื.

ืžืฆื ืืช ื ืงื•ื“ื•ืช ื”ื—ื™ืชื•ืš ืฉืœ ื’ืจืฃ ื”ืคื•ื ืงืฆื™ื” f(x) ืขื ื”ืฆื™ืจื™ื. )2(

. f'(x) ื‘ืฆื™ื•ืจ ืฉืœืคื ื™ืš ืžื•ืฆื’ ื”ื’ืจืฃ ืฉืœ ืคื•ื ืงืฆื™ื™ืช ื”ื ื’ื–ืจืช ื‘.

ื”ื™ืขื–ืจ ื‘ื ืชื•ื ื™ื ื”ืจืฉื•ืžื™ื ื‘ื’ืจืฃ, ื•ืžืฆื:

x ืขืจืš ืžืกืคืจื™ ืขื‘ื•ืจ ืฉื™ืขื•ืจ ื”ึพ )1(

y ื•ืขืจืš ืžืกืคืจื™ ืขื‘ื•ืจ ืฉื™ืขื•ืจ ื”ึพ

, f(x) ืฉืœ ื ืงื•ื“ืช ื”ืงื™ืฆื•ืŸ ืฉืœ ื”ืคื•ื ืงืฆื™ื”

ื•ืงื‘ืข ืืช ืกื•ื’ื”.

ืขืจืš ืžืกืคืจื™ ืขื‘ื•ืจ ืฉื™ืขื•ืจ ื”ึพ x ื•ืขืจืš ืžืกืคืจื™ ืขื‘ื•ืจ ืฉื™ืขื•ืจ ื”ึพ y ืฉืœ ื ืงื•ื“ืช ื”ืคื™ืชื•ืœ )2(

. f(x) ืฉืœ ื”ืคื•ื ืงืฆื™ื”

. f(x) ืืช ืชื—ื•ืžื™ ื”ืงืขื™ืจื•ืช ื›ืœืคื™ ืžืขืœื” , ื•ื›ืœืคื™ ืžื˜ื” + ืฉืœ ื”ืคื•ื ืงืฆื™ื” )3(

. f(x) ืกืจื˜ื˜ ืกืงื™ืฆื” ืฉืœ ื’ืจืฃ ื”ืคื•ื ืงืฆื™ื” ื’.

ื”ืžืฉืš ื‘ืขืžื•ื“ 5

11-

f'(x)

y

x

ืชืฉื•ื‘ื” ืœืฉืืœื” 4

x ืœื›ืœ e 0ax2 )1( ื.

0

x ืžื•ื’ื“ืจืช ืœื›ืœ f(x)

( ) 0 2( 3) 0 3f x x x& &= - + = =- )2(

( )f 0 6=-x 0= &

, ) , , )( (3 0 0 6- - ืžื›ืืŸ ื ืงื•ื“ื•ืช ื”ื—ื™ืชื•ืš ืขื ื”ืฆื™ืจื™ื:

/ื”ืžืฉืš ื‘ืขืžื•ื“ 8/

Page 8: 2014 summer B 807 a

ืชืฉื•ื‘ื•ืช, ืžืชืžื˜ื™ืงื”, ืงื™ืฅ ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317- 8 -

ื”ืžืฉืš ืชืฉื•ื‘ื” ืœืฉืืœื” 4.

ืœืคื™ ื”ื ืชื•ื ื™ื ื‘ื’ืจืฃ ื ืงื‘ืœ: )1( xื‘. 12-1-x 11-x

+0-f'(x)

34f(x)

0

x 1=- ืœึพ f(x) ืžื™ื ื™ืžื•ื ื‘ึพ

( )x =( )

'f e

e x eae2 2 3 2

ax

axaxax

$- + +

f'( 1- ) 0= ืœืคื™ ื”ื ืชื•ื ื™ื ื‘ื’ืจืฃ:

0

e eae2 0a

aa=-

-

-

2 4$ $- +

0

a 1=

( )f e1 4- =- x ื‘ึพ f(x) , ื•ื ืงื‘ืœ: 1=- a ื•ึพ 1= ื ืฆื™ื‘

( , )e1 4- - : f(x) ืฉื™ืขื•ืจื™ ื ืงื•ื“ืช ื”ืžื™ื ื™ืžื•ื ืฉืœ

ืœืคื™ ื”ื ืชื•ื ื™ื ื‘ื’ืจืฃ ื ืงื‘ืœ: )2( x 121x 11x

43f'(x)

-0+f''(x)+,f(x)

0

x 1= ืœึพ f(x) ืคื™ืชื•ืœ ื‘ื ืงื•ื“ื” ืฉื‘ื”:

( )fe

1 8=- x ื‘ืคื•ื ืงืฆื™ื” ื•ื ืงื‘ืœ: 1= ื ืฆื™ื‘

, e1 8-c m : f(x) ืฉื™ืขื•ืจื™ ื ืงื•ื“ืช ื”ืคื™ืชื•ืœ ืฉืœ

ืœืคื™ ื”ื˜ื‘ืœื” ืฉื‘ืชืชึพืกืขื™ืฃ ื‘)2(: )3(

x 11 f(x) ืงืขื•ืจื” ื›ืœืคื™ ืžืขืœื” , ืขื‘ื•ืจ:

x 12 f(x) ืงืขื•ืจื” ื›ืœืคื™ ืžื˜ื” + ืขื‘ื•ืจ: /ื”ืžืฉืš ื‘ืขืžื•ื“ 9/

Page 9: 2014 summer B 807 a

ืชืฉื•ื‘ื•ืช, ืžืชืžื˜ื™ืงื”, ืงื™ืฅ ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317- 9 -ื”ืžืฉืš ืชืฉื•ื‘ื” ืœืฉืืœื” 4.

yื’.

1 x

f(x)

3- 1-

/ื”ืžืฉืš ื‘ืขืžื•ื“ 10/

Page 10: 2014 summer B 807 a

ืชืฉื•ื‘ื•ืช, ืžืชืžื˜ื™ืงื”, ืงื™ืฅ ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317- 10 -

ืฉืืœื” 5ืžืชืžื˜ื™ืงื”, ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317 + ื ืกืคื— - 5 -

ื‘ื”ืฆืœื—ื”!ื–ื›ื•ืช ื”ื™ื•ืฆืจื™ื ืฉืžื•ืจื” ืœืžื“ื™ื ืช ื™ืฉืจืืœ

ืื™ืŸ ืœื”ืขืชื™ืง ืื• ืœืคืจืกื ืืœื ื‘ืจืฉื•ืช ืžืฉืจื“ ื”ื—ื™ื ื•ืš

) )ืจืื” ืฆื™ื•ืจ(. ) ( )f x xn x3 1

3 9 3 1,=

+- + ื ืชื•ื ื” ื”ืคื•ื ืงืฆื™ื” .5

. f(x) ืžืฆื ืืช ืชื—ื•ื ื”ื”ื’ื“ืจื” ืฉืœ ื”ืคื•ื ืงืฆื™ื” ื.

ืžืฆื ืืช ื ืงื•ื“ืช ื”ื—ื™ืชื•ืš )1( ื‘.

. x ืขื ืฆื™ืจ ื”ึพ f(x) ืฉืœ ื’ืจืฃ ื”ืคื•ื ืงืฆื™ื”

ื”ืฉื˜ื—, ื”ืžื•ื’ื‘ืœ ืขืœ ื™ื“ื™ ื’ืจืฃ ื”ืคื•ื ืงืฆื™ื”, )2(

x , ื”ื•ื 3.5 . a= x ื•ึพ e31

=- ืขืœ ื™ื“ื™ ืฆื™ืจ ื”ึพ x ื•ืขืœ ื™ื“ื™ ื”ื™ืฉืจื™ื

. a e31

2- ื ืชื•ืŸ ื›ื™

. a ื•ืžืฆื ืืช , ( )y n x3 12,= + ื”ื™ืขื–ืจ ื‘ื ื’ื–ืจืช ืฉืœ

. e313

4-x= ืœืคื•ื ืงืฆื™ื” f(x) ื™ืฉ ื ืงื•ื“ืช ืงื™ืฆื•ืŸ ืื—ืช ื‘ืœื‘ื“ ื‘ื ืงื•ื“ื” ืฉื‘ื” ื’.

ืžืฆื ืขื‘ื•ืจ ืื™ืœื• ืขืจื›ื™ x ื”ืคื•ื ืงืฆื™ื” f(x) ืฉืœื™ืœื™ืช ื•ื’ื ืคื•ื ืงืฆื™ื™ืช ื”ื ื’ื–ืจืช f'(x) ืฉืœื™ืœื™ืช.

y

x

ืชืฉื•ื‘ื” ืœืฉืืœื” 5

x3 1 02+ ,n ืฆืจื™ืš ืœื”ืชืงื™ื™ื: x3 , ืขื‘ื•ืจ 1 0!+ ืขื‘ื•ืจ ื”ืžื›ื ื” ืฆืจื™ืš ืœื”ืชืงื™ื™ื: ื.

0 x 3

12- : f(x) ืœื›ืŸ, ืชื—ื•ื ื”ื”ื’ื“ืจื” ืฉืœ

/ื”ืžืฉืš ื‘ืขืžื•ื“ 11/

Page 11: 2014 summer B 807 a

ืชืฉื•ื‘ื•ืช, ืžืชืžื˜ื™ืงื”, ืงื™ืฅ ืชืฉืข"ื“, ืžื•ืขื“ ื‘, ืžืก' 035807, 317- 11 -

ื–ื›ื•ืช ื”ื™ื•ืฆืจื™ื ืฉืžื•ืจื” ืœืžื“ื™ื ืช ื™ืฉืจืืœืื™ืŸ ืœื”ืขืชื™ืง ืื• ืœืคืจืกื ืืœื ื‘ืจืฉื•ืช ืžืฉืจื“ ื”ื—ื™ื ื•ืš

ื”ืžืฉืš ืชืฉื•ื‘ื” ืœืฉืืœื” 5.

( ) 0 3 9 (3 1) 0f x n x& ,= - + = : x ืขื ืฆื™ืจ ื”ึพ f(x) ื ืงื•ื“ืช ื”ื—ื™ืชื•ืš ืฉืœ )1( ื‘.

0

e313

1-x=

e e31

313

1- -1 )2(

0 x ื”ืฉื˜ื— ืžืชื—ืช ืœืฆื™ืจ ื”ึพ

. ( )x x

n x dx3 5 3 13

3 19 3 1

e

a

31

,= - + - +

+

-

b l# ืœื›ืŸ ื”ืฉื˜ื— ืžืงื™ื™ื:

0

. ( ) ( )n x n x3 5 33 3 1

69 3 1

e

a2

31

$,,= -

++ +

-: D 'y , ืœื›ืŸ: ( )

xn x3 1

6 3 1,= +

+ืžื”ื ืชื•ืŸ ืžืงื‘ืœื™ื ื›ื™

0

. ( ) ( )n a n a1 5 3 1 3 1 4 02, ,+ - + - =

0 ืคืชืจื•ื ื•ืช ื”ืžืฉื•ื•ืื” ื”ืจื™ื‘ื•ืขื™ืช

( ) , ( )n a n a3 1 2 3 1 34

, ,+ = + =- ) ื”ื: )n a3 1, + ืฉื”ื ืขืœื ืฉืœื”

0 0

a e312

=-

-e313

4-a= , a ืœื ื‘ืชื—ื•ื ื”ืขืจื›ื™ื ืฉืœ

0

a e312

=-

yื’.

x

f(x)

31-

e3

131- e

313

4-

x e31

313

4

1 1-- ) ืขื‘ื•ืจ ) 0' xf 1 , e

313

1-x2 ) ืขื‘ื•ืจ )f x 01 ืœืคื™ ื”ื’ืจืฃ:

0

e e31

313

134

- -x1 1 f'(x) 01 ืขื‘ื•ืจ ) ื•ื’ื )f x 01


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