>
^QDE
a LQEF
(goc o dinhQchung), do dt: f;FE: GD fzl
Ta sE chimg minh rang fFa : fED.
OC thay ring LTAF <n LTDB (hai goc & dinh 7
a6l einrr vi, trFD : IED), rut ra # : #
o TF.TD : TA.TB. Tuong W, LTAC a LTEB (hai goc o dinh rdoi dinh vd IC-E : IEEy
M(}T TiNTT CFIAT
VIET HAl
,TCTB
rbtra fi : TE o TC.TE : TA.TB.
Tt d6 vd ding thfc tr6n c6 TF.TD: TC.TE
TF TE
\
- TC TD ru tl6 vd FTC: ETD c6
LTFCcnLTED,ritrafFd : rEn (3)
. Tri (1), (2), (3) suy ra dFE : 5Fi * fFC+ QFE : OEF + TED + QED: QEF .a + QFE : OEF + TED + QED: QEF .a
DINH HUONG 2. Sri firng cdctamgi6c d6ngdang dO chuy6n hai goc cAn tim sang c6c g6c dang dO chuy6n hai goc cAn tim sang c6c g6c kh6c tuong img bing chirng sao cho dE x6c
dinh duqc -5i qrrat hQ gita hai g6c m6i. Cdch gidi 2. Chtmg minh nhu o c6ch gi6i 1
(h.1), ta co
Hinh I
Tn LOCF <n LOFE rhtra 6dF : 6FE @)
rn LQDE a LQEF rntra 6DE: @ (s)
ri LTFC a LrEDrhtra fdF = fDE (6)
Tt (4), (5), (6)
"uy *ffi : 6di: lSoo - fu
:180o - rDE: fu: dEF t
,z",sr
DINH HLIONG 3. X6c dinh mot ducrng trdn
sao cho g6c OFE vd g6c QEF d.e:tld g6c tao (adsbygoogle = window.adsbygoogle || []).push({});
bdi.ddy EF voi ti6p tuy6n FO vd v6i ti6p
tuy€n EQ .
Cdch gidi 3. Duolg tron duong kinh Oe clt
dopn thing TE tai di6m K vd c5t Oopn ttring
TF tqi di6m .r b. 2).Hai duong Uing Ol va8K lil hai ducmg cao cira tam gi6c TOe n}n 8K lil hai ducmg cao cira tam gi6c TOe n}n
giao di,5m P ci.r. chring ph6i nim tr6n ducrng
cao thri ba TH, tuc ld c6c di6m p, A, T, H
thEng hdng.
Trong tam gi6c w6ng AOQ c6
oH.oQ: oA2: ofr
X6t hai tam gi6c r.u6ng AOPH a AOeJ (g6c
o chung vit 6FE : 6D do c6 cpnh tuongimg r,udng g6c), rut ra img r,udng g6c), rut ra
OH OJ
oH.oQ: OJ.OP (8)
oP oQ*
Tt (7), (8) suy ra Ofr : OJ.Op,do d6 tam gi6c
OFP vudng 0 F. Tri db pF ld ti6p tuyt5n cria
duong trdn t6m O, suy ra pfr : pA.pB. (9)
Lfp lu1n tuong t.u, d6i voi tam gi6cw6ngAOect: Qfr : QA2 : QH./O, tu LepH a LeOK, ct: Qfr : QA2 : QH./O, tu LepH a LeOK,
ritra QH.QO: QK.ep. suy ra Ofr : eK.ep,
do d6 tam giitc QEP vu6ng 6 E. Tt d6 pE lit
tiiSp tuy6n cua duong tron tdm e, suy ra
Tri (9) vd (10) c6 PE: pF, d6ng thcri FO vd
EQ ddu ld titip tuy6n cta duong tron t6m p vd
ctng ch6n r;rms FE n€n 6FE : f;rt a
Ba c6ch chimg minh tr6n d6u chi sri dpng c6c
ki6n thric Hinh hoc 9, cdn n6u da bi6t
Phucrng tich cua mQt di6m O5i vOi ducrng
tron o Hinh hoc 10 thi c6 thOm c6ch giii
ngin gon hcrn sau d6y. (adsbygoogle = window.adsbygoogle || []).push({});
DINH HUON'G 4. Sri dr,rng phucrng tich cira
mQt di6m COi vOi cludng trd; d6 chrmg to b6n
di6mfl, C, D, E ctng nim tr6n mQt duong tron
vd g6c OFE liL g6c tao bcri d6y EF v6i ti6p tuy€n FQ, g6c QEF ld g6c tao boi ddy EF v6i ti}ptuyenflQ.
TONN HOC- cfucii$e cfucii$e
Cdch gidi 4. oXltPhucrng tich ctra di6m f d6i
v6i ttudng tron tdm O vd d6i v6i duong tron
tdm Q (h.2) ta c6 TD.TF : TA.TB : TC.TE, do
d6 b6n di6m f,, C, D, E ctng nim tr€n m6t
ducnrg t:rdn 3.
o X6t Phucmgtich cua di6m O d6i v6i rlucrng
trdn tdm Q vd rlulng rrdn ? c6 OF : OA2