. Xdt k= B Tir (l) c6 n z= l7 a2+ 77 24 (4)
sP SP.SN SM2
-=
_ /::\
PN PN.SN MN2 b2 \rrl
sau cring, tit (i) vd (ii) cung thu cluoc 2[
"ai !1
DA DA
nhtt (5) 3 tr6n.
-Z) U9t sd ban srl dung phrrong ph6p toa d6 cirng cho
k6i quA nhu ldi giai tren, song d6ng tidc nhi'du ban d6
giii sai. 56'cdn lai cflng g:idi dring nhrrng kh6ng tinh to6n
duoc gi6 tri 16n nh{t cria th6 tich trr di6n ABCD theo 6 vi
c md chi cho gi6 tri d6 dii cria MS = { ad u@BCD)
'12
dat gi6 tri cqc dai,
3) Ban Trinh Vd.n Nam, 12Ar, THPT Phan BQi ChAu,
NghQ An cdn dd xuft
^vd glAi bdi tor4n tdng qu6t hdn bing c6ch thay trung didm M cria canh BC bAi m6t didm
tiy y thu6c do4n BC *,
# = h (k > 0) vi cho kdt qui
utaABCD)
= *:W. i2([+1) Ding thirc xiy ra <> sM =
lb-
U
,lii_ . (Bdi to6n tr6n rlng vdi 9:6 rri A = 1).
4) NgoAi hai ban Vfr Manh Tudn vd Trinh Vdn Nam
c6c ban sau dAy c6 idi grAi tudng d6'i gon ging ; Vinh
Phric : Trdn Trung Dfing, iOAt, Ne"yA" ian Ngoc, tA
Trudng Sor2, 1141, THPI chuy6n, Trdn Vdn Euynh,
10Al THPT Ng6 Gia ft, LQp Thach; Scrn Lat T6 phttong
Nhung, 1142, THPT Mai Son, Son La ; Nam Dinh :
Pham Cao Kj,, 1185, THPT Hai HAu A ; HAi ph6ng:
Phq,m D.uy Tilng, t2A2, THPI Kidn An; Thanh H6a : Bili Khac KiAn. fi THPT Lam Son, Le Ngoc Du, t0At0,
THPT I,6 Vdn Hrru, Thi6u H6a; NghQ An ; LA Vdn Ltttng,
rrT, THPI Hi Huy TAp, TP Yinh, NguyAn Viei Kh6i,
1rA1, THPI Phan B6i ChAu ; Hd Tir,h t Nguydn Ngoc
Anh, Lt To6n KlS, THPT chuy6n Hd Tlnh; QuAng Tri:
Nguyen ThiAn Nhdn,11 To6n, THPT chuy6n Le eui DOn;
Thiia Thi6n - Hud : Nguydn Tudn Minh, 11 Todn,
THPI Qudc hoc - Hud ; Dd NEng z NguyAn Txdng Hudn,
1U1, THPT LO Quf D6n ; QurAng Nsdi : Thdi Thanh
Tdn, L1A9, THPI Drlc Phd I ; An Giang: Trdn eu6t \A.ne, rcet THPT Iong Xuy6n ; Bd Ria - Virng TAu:
Trdn Van Linh.THY| t e Quy Don. Vung Tdu.
NGUrrEN DANG PHAT