- Sir dung B1; (lA Yin a, p 7 ld cdcg6c phdng cila rnbt gbc tarn dien, t'd A la gdc nhi diin cila tam diAn db
1241, TIIPT Nam Sdch ;Hh fin h: Trdn Dac Phi, ll
Li, THPT chuyOn He Tinh I Bdc Giang t DurmgTrung Hỉu, Pham ThíManh, l2B, THPT chuy€n Bac Giang ;
Nghe An : Nguy4n Bili Thi4n, llA3, Nguydn Manh
Thdnh, ,{3, K3l, Nguyin Khdnh Hung. 12A3. K3l, TFIPT Phan BOi ChAu, Ngh0 An ; Hung Ydn: Pham
Qu6c Vier, Nguy4n Tudn Anh, l2 Li, TIIPT chuyOn
Hung Ydn ; Hi N6i z Bii Phi Anh,12 Li, THPT Hn Ndi
- Airsterdam ; Thanh H6a Trrin Dai D*mg, ll F,
TIIPT chuyOn Lam Son; Th:{i Nguy6nl..ChuTud'n Anh, 12 Li, THPT chuydn Thdi Nguy€n : Tien Giang: Irdn
Thi M! Phtrong,12Li, THPT chuyOn Ti6n Giang ; Vinh
Long: Hu)nhThanh Binh. l2L. TIIPT chuy6n Nguy€n
Binh Khi0m ; Qu6ng NgAi : NgayanTdn Dut, 12Li,
THPT I-e Khidf ; B)nh Dinh : Ngrrldn llfnr Nltlin, 121 .,
'l-l tPl chuyen Le Quy l)tln l l'htíl'hr.t: N1;tr.vt'tr'Minlt
Tdn, 12A4, THPT Thanh Thuy ; Gia Lai: Biii Quang
Todn,lZC, TIIPT Hing Vuong.
MAI ANH
&K
Rj vd Rạ
Ldi giiị Goi R, Ii di€n tr& tuong duong cira
mach ngoli ta c6 : Pn = ÍRn= [- '-l'O,.
\1(n +r/
rhay ' sd : t2= [=+]'R, = nl - tsn,+
t Rn+6) tt tt
36 = 0 (1) Suy ro R, = 3 (Q) hoac R, = 12 (Q).
Khi K m& thi & = Rrn = Rr * R: (2). Cdn khi K d6ng rhi R, = Rr, = *l!j? (s)
R,, +R2 +Ro
TU (2) vn (3) ta thdy chi c6 thd x6y ra trudng
h9p Rr, = 12 (O) vd R2n = 3 (O).Tt d6 ta tim
dutrc : 1i3 = 19 (O) ve R+ = 3(O)
NhAn x6L Ci{c ban c6 ldi giii gon vi d6p sd dfng :
Bdc Ninh z NguỷnCdng Drdng, t I Li, T}IPTchuyen Bac.Ninh ; Bdc Giang t PhamThéManh, DurmgTrung
Hieu, t2B, THPT NK Ngo S! Licn ; VInh Phtic :
Nguyin Ngoc Hung. -Ngo-VieịCtung. I I A3. Nguyt;n
Minh Phtong, Nguy€n Van Bdc, l0A3 THPT chuyOn trnh Phf_c ; Phri Tho z Nguy€n Hfru Todn, l0 chuy€n
Li, NguyAnVfi Long.l lBl, TIIPT chuy0n Hing Vrrcmg; IImg Y6n z Pham Qu6:cViit, Nguy€nTudn Anh,l2Lị
THPT chuy€n Hung YOn ; NChe An z Ii AnhTudn,
llAl, Nguy4n Bii Thi€u, llA3, Nguy4n Drtc Tilng, I I A2, THPT Phan BOi Chau, Vinh : H6i Phdng : Pham Tudn Hiip.l I Lf. THPT NK Trdn Phri I HAi Duong : ll
Hodng Dfrng, 1l Li, THPT chuyOn Nguytin T.rii ; Binh Dinh z N guy|n Htu N hdn, 12 Li THPT chuyOn Ld Qu j
Ddn ; Hh N6i : BDi Phi Anh, 12 L:t T}JP| Hn Noi -
Amsterdam ; YOn B6i z Trdn Qudng Ktuii, ll Li,Kl4,
THPT chuyen Nguydn Tai Thnnh : Dak Lak: Nguyin
Thdnh Nbi, l lCT. THPT Nguyr5n Dụ TP Budn Ma Thu6( I D6ng Thdp :Thdi Phan,l2T, TIIPT TX Sa D6c;
Tic^n Giang zTrtcrng HuynhThanhTrrtc,12 L[, T]IPT
chuy€n Ti€n Giang : Quing Ngei : td Hd KiOt.l2A2.
THPT Drlc Phet l, N guye n Tud'n Duy, 12 Lị THPT LC
Khidt ; Thanh IJ6a z Nguy€n Manh Ctdng, loF,Triin
Dai Drong, IlF, THPT chuy6n Lam Son, L€ T'hil'un
Anh. l0Al, THPT Ddng Son I ; Ninh B\nh: Ngb Bdo Ngoc, I lA3, THPT Luong Van Tuỵ
I
I
NII[fiNG DON VI DO
nnr Ncudu ru cuOc sdxc
Ban đ bidt don vi do chi6u dhi cira Anh - M!
foot (= l2inch = 30,5cm) thinh !a clitiu dhi trung
tirn i Ua" chin ctra nguor Au - My Cdn inch, yard,
sea mile c6 xudt xf til nhtng chidu dhi nho nhi ?
Ban c5 bidt clon vi do niro kh6c vb xudt xf
ctra n6 ?
vU o6 QUAN