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tludng trdn S c6 t6.rn O, li6n kinir rT lA dutrng
tr&n ngoai ti6P tti' glrio niY'
Biug nr$t cielt rri-'in tuorrg tLr circ tliir:g th(c
(i), (2), (3)' ta dinh nghia:
Trrong tu ndu goi lit, Ez, Es !A tirn dudng
lrdn OIL cfra cdrc tam giAc ;t2,431i+ ' '4sAaAt ;
,44.t1.{r ta r," :
EE1-*: liE2 -' ;''1;3 :::: ;)f;!' .
Nhu vAy cac <1i6m ll,t. Ez, Ez, E4 nirm lrdn
duong tron. CJle eira tir giAc Jl"1z'leAa, hay cAr
rludng trdn Olc cira brie iaur giec {::'13'14' Agrll3i'
.4+.ttiiz, JrAzAs cJit tri::rrr tai iirlrn l:r'
Cu6i Cirng, e6c l;*r i:li.,; ir'; 1!i1' 11;. i:ri:rir iinh
elrJt sat, ddr':
Tinh chdt 5: Goi Mt, XXz, tr13' lla l:]n lttgt
ih trong tArn cria e lLe tam giiic. AzAele, '{s'4aAi'
,ladlAz, ;ltAzAt tht 4 doan thlrng 11!'11' 'l'M2'
.13i'tf3, d.lMa sE ciit nhau lai rnQt ili6m '11 chinl:
tA tLi7ng tArn cira liL giae LrSi 1i6p 3t"1:ls4'r vir:
.\;Irtti 3l tli: 3 (i: 1, 2, 3, "l)
Iihdng nhtng thij, cilc ban cr)t; cri ihi: i'iiii:lg
minh dusc ba tiuh rr,rtit r'iii ti:t ';] nir* :
Tinh chdt 6' Goi ifil ld '.rttng di6m rloan A;3;
(i*j) t ri ,4f Iir gioo clilrn chring cfr:r cat: doan
itrirqg ^!Ii;Msr ,-Ol (r, /, ii. ir li'rnrii irr-'ilr -"i eira
(1, !, 3, {),
Tinh chdt 7 : Ci,rc itoan tlrrrng 't1Ili, 'lzllz'
A3ttg, AaHt cit nhau tai mdt cliSrr' E Id tdnr
A"ong trdn O-ie cfia tu giirc nQi ti6p lr'4zAsAa'
.f inh ctrdt 8 : Siu tluong vudtn{ goc ha tu
trung tlibm c&a m6t canh (ha1'n'rot rtrucrng ch6o)
toi c-anh d6i di6ir {hay cludng r:heo eirlr iai) cirng
cit nhau iai lAm slrlrirrg 1r'tn {'1i* ciirr trri giir:
ndi lidp Jt.1z.1:i.{4.
Nhu virv cuc batr se hinir dttt'ig ril cr'ieh m&
rArrg lrl,ii niQnr drio'n11 irdn Ole '''i rlurilg llirlg
(jie cno rn$t tla giac rriii lit^'i) b'i1 kj-' Chting
ta dinh nghirt bilg qui nap: giri siL i:11 c khf,i
ni€m tr€n cll dinlr ughir rho {'dL tit circ rla giic
n6i tiFp c6 sd canh nh6 hrrn n: thd thi:
Fsinh nghiLt 1' : Truc tirn li eia -rr
* gidr
,11J2.13...J6 l$i ti6p li-cng drrdr:g tit)u S ld giao
Ai6rn cnung ciia n drrt}rtg lr.on bingl (tuolr[i trdn
S vi tri t.im tai "6" ii1;:', lit:l i:i:a rti*'1 )'- giec
iao b&i (n'- 1l <?inh eri:r iz - rrii:c '1t'4'r'4:1""'1t'
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AtAz,.'An ndi ti6p duirtg trdn ^S la-grao t1i8rn
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gi,ec vtii trong tAItl o&n (n-1)-giac iao boi ciic
Iinh' *on lai. Nltu v.ly ta 's0 cc ll{ chi:t irong
.il' oonr, ti&ng nev theo t? sd (n- l) : 1 hb tri
dinh cria n*giAc vA :
AM = (O,\ + n.1? '... I QAntrn,
-Ei rth ngl,io 't : Tr u c t fr nr tt c irr
{t Ar .13 Aa nOi ti6p troug iltrong trt'rti
bun kinir Ii 1A diBm lhila mdn:
@ € 4 4 d
O lt :0Ar * OAz + OAs i- tlA+
iri gidrc
S. tem Lt,
(2')
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Oinh nghia 2: Trong t0m '\y' cirrr..tl- Cie"
Ar,qf es.la"noi ti6p tlong tlutrng tron S' tAr;r O'
Lin kinh ll ld di6m ttr6a mdn:
€ 4 s 4 €
ail:(tl4) (oa\+ ij|, + tiat + OL4i (1')
Dinh nghia na-v hohn loln phri lro'p v6i
khti niQm"trqng t6'ar nra ta bi6t tir trutlc ddn
rr*',' (c{c bqn trr ehirpg rntnh)'
Bitth ngltLtt 3; Ndu ff Ii trrc t6rn eira tii gif,c
Irezasan"oOi ti6p trong ilulng tron-'S'.tini O'
bln kr,rli /? thi duong trdn v6i tim E li irung
ililrn ctia OH, Lrh4 kinh tl,'2 iluoc goi lb' dudng
trdn Ole cria tu gi6e nOi ti6p '4t rlz ;1g ;1+' Nhu
v iv 4 diErl O, /,l: E, fJ sE riinr trdn mrjt^fluong
;il?r;,;;;,,g',r.,ing tln:" sqi li drrdrns th8.ns ak
c&a tu giiic n6i tidP 1r '4xA3 Aa'
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gihc n0i ti6P .At.4zA3Aa.
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.lnir.fr. ,1142Al; th6 thi cSc duong tlr)n tiiur lA
it,-Hz, H3, ll 4 co cr\ng bin kinh fi (bin hintr
J,roni t.an nsoni ti6p) sE t'il lha.u 1:ri nr{'1'
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