algebra
BADDACȡBDtDC5t Ȥȡ;Ѥơt^229/5
cosȡ4/5ꡤsinȡ3/5sin2ȡ24/25
äơABC1/231524/25108/5(cm2)
829ڡ 0:14:06 48366
٥륯åĥ
¡äĤ˲­ȡɤȤ롣
ȣġģɡ15ȡɡ15ʤΤ򤽤Ƥȣġģɡ510ʤΤǣɡ12345ľѻѷǣãɡ9492ߡ6/5ˡ21.6ˤʤޤ
829ڡ 0:17:41 48367
ߤ
šáգ⤵ջѷţäꡢѷ£ä
ʤȤȤǤޤ

ŪˤϥäݤɡȤꤢʤߤΣľѻѷ
ѤǤ
829ڡ 0:18:29 48368
鯤ο
ޤϵ
ѤΣʬ顢BDaȤȡDC5a
ABDȢADCˤĤѦȤˤĤ;ȡ
cosȡ(25-a^2)/2*3*4)(241-25a^2)/(2*4*15)
ꡢa^229/5
äơcosȡ4/5sinȡ3/5sin2ȡ24/25
äơABC3*15*24/25/2108/5
//
829ڡ 0:19:13 48369
鯤ο
algebraȴפǤ
829ڡ 0:20:26 48370
ˤ⡼
Ĥ̤˱Ĺá15š12ãš9ľѻѷǤ褦
ŤĤαĹˤĤ롣
ȡţá54
ãġᢤţá1/318
¡á£ġģá1:5
£áᢤãġ6/5108/5
ʾ

β٤γǤǤʢڥåѥåǤ㲼˴ˤ⡼
¡ 829ڡ 0:42:28 HomePage:ͥĤäƤߤ48371
Mr.ǥ
ܣ£ġᦨȤ
£=£+ãġ(1/2)x12xsin+(1/2)x60xsin
=36sin
ޤ
£á(1/2)x45xsin2=45sincos.......
36sin45sincos
cos4/5sin=3/5

£á108/5
ʤޤäؤǤ줫黻ǹͤޤ
829ڡ 0:31:53 48372
ǯ
BADʿACȤθEȤ롣
٤δط顢ABEAE=AB=3ջѷ
BE4*(3+15)/15=24/5
ABE˿򲼤Ƥ­HȤ
AHE3:4:5ľѻѷAH=9/5
AEB=(24/5*9/5)/2=108/25
ABCѡ108/25*15/3=108/5

829ڡ 1:09:14 48373
鯤ο
>48371

Ĥ̤˱Ĺá15š12ãš9ľѻѷǤ褦 ŤĤαĹˤĤ롣

Ϸ̤ȤƤȤ줿ɡΤ褦EΤϼʤǤ礦
829ڡ 0:45:05 48374

ADĹBA=BE=3ȤʤEȤ
ADC梤EDBȤʤΤDE=34/15=4/5
BAE˲­HȤEH=(4+4/5)/2=12/5
3:4:5ľѻѷBH=9/5
ABC=ABD6=1/249/56=108/5
829ڡ 0:48:43 48375
⡼ޥ
ޤŪʤΤޤʤ褦ʤΤ...
΢ޤʤơĤäB'DCγB'DCʬ...
(15-3)*(3/18)=2
so...3:4:5
⤵3*4/5
so...
(3+15)*(3*4/5)/2=108/5
829ڡ 1:17:00 48376
Ȥ
ɸǤβ3ǤΤǡޤ1!

Ѥʬ
ɸB(-a,0),D(0,0),C(5*a,0)Ȥ
B濴Ĺ3αߤD濴Ĺ4αߤθA
D濴Ĺ4αߤC濴Ĺ15αߤθA
ƱxɸȤa
BC(=6*a)*Ayɸ/2=ABC Ǥ롡XMaxima

part(solve([(x+a)^2+y^2=9,x^2+y^2=16],[x,y]),2)$
part(solve([(x-5*a)^2+y^2=15^2,x^2+y^2=16],[x,y]),2)$
ev(3*a*rhs(part(%o1,2)),part(solve(factor(rhs(part(%o1,1))-rhs(part(%o2,1))),a),2));
108/5()
˭ԡ 829ڡ 1:23:45 MAIL:fttnm528@ybb.ne.jp 48377
Ȥ
ˤ!!

ɸA(0,0),D(4,0)Ȥ
A濴Ĺ15αߤD濴ĹaαߤθC
DȤľBCޤꤳ
ľAB:y=-Cyɸ*x/CxɸȤθB
AB=3aޤ4*(Cyɸ-Byɸ)/2=ABC
XMaxima

part(solve([x^2+y^2=15^2,x^2+(y-4)^2=a^2],[x,y]),2)$
part(solve([y=rhs(part(%o1,2))*(x-4)/(rhs(part(%o1,1))-4),y=-rhs(part(%o1,2))*x/rhs(part(%o1,1))],[x,y]),1)$
factor(rhs(part(%,1))^2+rhs(part(%,2))^2-9)$num(%)/9$
solve(factor(expand(part(%,1)^2-(%-part(%,1))^2)),a)$
ev(2*(rhs(part(%o1,2))-rhs(part(%o2,2))),part(%o5,12));108/5()
˭ԡ 829ڡ 2:02:22 MAIL:fttnm528@ybb.ne.jp 48378
Ȥ
!!!

ɸA(0,0),B(3,0),D(sqrt(16-a^2),a)Ȥ
tan2ܳѤľACޤꤳ
ľBD:y=-a*(x-3)/(3-sqrt(16-a^2))θCޤ
AC=15ǻʿaޤAD(=3)*Cyɸ/2=ABC
XMaxima

trigexpand(tan(2*a))$
factor(ev(%o1,tan(a)=a/sqrt(16-a^2)))$
part(solve([y=%o2*x,y=-a*(x-3)/(3-sqrt(16-a^2))],[x,y]),1)$
part(num(factor(rhs(part(%,1))^2+rhs(part(%,2))^2-15^2)),2)$
solve(factor(expand(part(%,1)^2-(%-part(%,1))^2)),a)$
ev(3*rhs(part(%o3,2))/2,part(%,6));
108/5()
˭ԡ 829ڡ 2:22:22 MAIL:fttnm528@ybb.ne.jp 48379
ֿء׾ι
Ȥꤢ;ȤäưŻޤ
cos@=4/5 Ȥʤäƽޤ
829ڡ 3:57:35 48380
ֿء׾ι
Ȥꤢ;ȤäưŻޤ
cos@=4/5 Ȥʤäƽޤ
829ڡ 3:57:56 48381
ֿء׾ι
Ȥꤢ;ȤäưŻޤ
cos@=4/5 Ȥʤäƽޤ
829ڡ 3:58:01 48382
ֿء׾ι
Ȥꤢ;ȤäưŻޤ
cos@=4/5 Ȥʤäƽޤ
829ڡ 3:58:01 48383
ֿء׾ι
ߤޤ󡣽񤭹ߥܥȿߤäΤǥåפޤ
829ڡ 4:02:49 48384

CABʿԤľADαĹȤθPȤ롣
ACP2ջѷǤѤ24*9/2=108
CAD=108*4/24=18 CPD=90
ABD=90*1/25=18/5()
ABC=18+18/5=108/5
ʤ졢Ƕ褦ʻä褦ʵ
829ڡ 4:22:33 48385

CABʿԤľADαĹȤθPȤ롣
ACP2ջѷǤѤ24*9/2=108
CAD=108*4/24=18 CPD=90
ABD=90*1/25=18/5()
ABC=18+18/5=108/5
ʤ졢Ƕ褦ʻä褦ʵ
829ڡ 4:29:23 48386
ˤ
٥ȥѤޤ
Ķļˡ 829ڡ 6:00:13 HomePage:ޤޤ48387
Ѥ
ADĹC̤äABʿԤľȤθEȤ
AECջѷˤʤѤ108ޤé夤
äȡġġդ޷Ķä
829ڡ 9:53:55 48388
Ȥ
#48379
tan2ܳѤdzѤ2ܤΤǤʤ
tan2ܳѤεդȾʬˤǸa2
6äΤѤޤ!!

ɸA(0,0),B(3,0),D(sqrt(15^2-a^2),a)Ȥ
tan2ܳѤεդľADޤꤳ
ľBD:y=-a*(x-3)/(3-sqrt(15^2-a^2))θDޤ
AD=9ǻʿaޤAD(=3)*Cyɸ(=a)/2=ABC
XMaxima
trigexpand(tan(2*a))$
solve(%=a/sqrt(15^2-a^2),tan(a))$
part(solve([y=rhs(part(%o2,2))*x,y=-a*(x-3)/(3-sqrt(15^2-a^2))],[x,y]),1)$
num(factor(rhs(part(%,1))^2+rhs(part(%,2))^2-16))$
ev(3*a/2,part(solve(factor(expand(part(%,1)^2-(%-part(%,1))^2)),a),2));
108/5()
˭ԡ 829ڡ 12:20:12 MAIL:fttnm528@ybb.ne.jp 48389
ޥ
򳫻Ϥ40ʬ֤ǤפȻפä顢245http://www.sansu.org/used-html/index245.htmlˤȴפƤޤäΤǡѤơ夭ޤ֤˹äɤä...
MBP 829ڡ 12:46:02 HomePage:48390
Ȥ
#48378

ɸxƱC(sqrt(15^2-a^2),a)Ȥ뤳Ȥ
ľCDޤ׻ƥå׿
Ǹa6 12äΤѤޤ!!

ɸA(0,0),C(sqrt(15^2-a^2),a),D(4,0)Ȥ
ľCD:y=a*(x-4)/(sqrt(15^2-a^2)-4)
ľAB:y=-a*x/sqrt(15^2-a^2) 2ľθB
AB=3껰ʿaޤAB(=3)*(Cyɸ(=a)-Byɸ)/2=ABC
XMaxima

part(solve([y=a*(x-4)/(sqrt(15^2-a^2)-4),y=-a*x/sqrt(15^2-a^2)],[x,y]),1)$
num(factor(rhs(part(%o1,1))^2+rhs(part(%o1,2))^2-9))/9$
ev(2*(a-rhs(part(%o1,2))),part(solve(factor(expand(part(%,1)^2-(%-part(%,1))^2)),a),6));
108/5()
˭ԡ 829ڡ 13:12:11 MAIL:fttnm528@ybb.ne.jp 48391
hide
ˤ⡼ƱˤDz򤫤Ƥޤ
ŷ🎸 830ʶ 7:22:47 48392
ϺĹ
˺Ƥ񤷤롣⤦ष褦Ȼפʤ顢ޤäꤷƤޤ
830ʶ 11:56:46 48393

D̤ACʿԤľABȤθEȤȢADEջѷ
ABCȢEBDǡ椫AE=DE=2.5ʤη׻ʸȤäƤޤä
EAD˿ߤջѷADE3:4:5ľѻѷʬ䤵Ȥ狼
ִݤγ٤3:4:5ľѻѷ45Ƕޤ٤Ȥ狼ΤADդȤȤBCι⤵狼ꡢ21.6

830ʶ 12:34:04 48394
Ф
ѴؿϰפBADȤȤȻѷABCѤ̤ɽ45sin2=72sinȤcosȡ4/5sin=3/5
830ʶ 20:56:04 48395
Ϸ
򸫤ƤߤȣգѷΤ¿Ǥ
񤫤ƤʤΤ褦ǤΤǽ񤤤Ƥߤޤ

Ĥ¤ʿԤäȤθȤȤޤ
ģȤϣգѷǤ
ȤĤ˿ɤȤޤ
£áġߣɡߡʣáȡˡߡʣ£áģáˡࣲ
21.6
Ȥʤޤ
831ڡ 9:53:22 48396
leafirby
ϰϤΤ񤷤Τ
cos(A/2)=4/5,45sinA/2wolformalphaꤲޤ
91 3:25:42 48397
leafirby
ϰϤΤ񤷤Τ
cos(A/2)=4/5,45sinA/2wolformalphaꤲޤ
91 20:02:26 48398
Mr.ǥ
ϰ()DzľޤƱˡʤʤΤǽ񤭹Ǥߤޤ
B,CľADˤ­򤽤줾졡B',C'ȤAD=Ȥ
ABB'梤ACC'ꡡAC'=*(15/3)5
DBB'梤DCC'
DB':DC'=BD:CD=AB:AC=1:5
衡(4-x):(5x-4)=1:5
x=12/5
ABB'ϡ345ľѻѷBD=1.8CC'=9
ABC=(1/2)*4*(1.8+9)=108/5
92ʷ 11:23:20 48399
߼Ψ繥ʹ
3:4:5ľѻѷäƤΤΤäƤоǤ򤱤ޤ͡Ǥ
94ʿ 20:03:33 48400