<span class='text_page_counter'>(1)</span><div class='page_container' data-page=1>
so
crAo
D
TAO
xi
rm
rUYEN
sINH
LoP
to
rHPT
NAU
Hec
zozo
<sub>- </sub>
zozt
Kh6a ngiry
171712020
oAp
Ax-THANG
DIEM
M6n
thi:
TOAN
0'5
1)
T{nh
gid
tr!
cfto bi6u thrbc
A
khi
r
<sub>- </sub>
4.
Thay
r -
4
(thoa mdn
DKXD)
vdo bitiu
thric
A,
tinhdugc:
.4 3
4
GI
0t
lr0
2)
r-Vr+1
1
1
2
-
(c-r)(.6+r)
(c
(l;
B-
3
J"
-t
3
+
)-(
Ch*ngminh B
<sub>- </sub>
+
Jr
+t
.6+r)
J-"
+s
,(l;
<sub>- </sub>
r)
0'5
BNi
I
2,0 didm
3)
Tim
ttit
crt
gid
tr!
crta
r
it|
bi\u
thtbc
P
<sub>- </sub>
2A.B
+
J
<sub>" </sub>
dqt
gid
tr!
nhd nhdt.
P-2A.B+J;:#r+J;
Tac6: P
<sub>-2 </sub>
-++J;
-2-
+>
0 voimoi
r
>
0.
Jr
+z
Jr
+2-Suy
ra
P >
2.
Dingthric
xtty
rakhi
vd chi
khi
r -
0
KL:
r -
0
thi
bi6u
thric
P
dqt gi6
tri
nhO nh6t.
l15
VAn t6c
di
xe dpp cira
An
la
r
*
I
(km/h).
Thdi
gian
An di
b9 ttr nhe
An
dtin nhd Binh
l'
a
<sub>- </sub>
3 (gio).
...
+
r'
+9r
<sub>- </sub>
36:
o <+
(r
-
3)(" +12)
-
o <+
,
Tinh
vQn tbc
iti
b? crta
An.
LAp lupn d6n d6n phucrng
trinh
3
Thcri gian
An
di xe d4p tir nha Binh v0
Gqi v0n di b0 cua
An lir
r
(dcrn
vi: km/h, u
>
0).
r-3
r--t2
3
nhaAnh
<sub>r+g </sub>
Gio).
33
r r*9
4
Bii II
2,0 diam
I
1)
Di6m
v
Dfp
6n
</div>
<span class='text_page_counter'>(2)</span><div class='page_container' data-page=2>
kiQn
lopi
r
12 , thu 14i
r -
3
thoa mdn y6u u
bii
to6n.
KL
hqrp di
t6c di ctra
An
la
3 km/h.
0,5
2)
Tinh
diQn
tich
bi
mfit cfia qud bdng bdn.
S
<sub>- </sub>
4trR2
x
4x
3,14 x22
<sub>- </sub>
50,24(.-').
bc mdt cira
qui
b6ng ban do
li:
DiQn tfch
Ir0
r)
Vdi
b
<sub>- </sub>
1
+
+ -
1
+
<sub>u </sub>
:
2(thoam6nDKXD).
y
<sub>-l </sub>
v
KL:
hQ phucrng
trinh
co nghiQm duy nh6t
le
(r;
y):
(r'r).
Gidi hQ phwong
trinh
<+ ....
e
2r
*
3b
<sub>- </sub>
5
4r
<sub>- </sub>
b
:
3
2r* 3 :b
y
<sub>-l</sub>
4r- 1 :3
y
<sub>-l</sub>
DKXD:
U
<sub>=L.</sub>
1
DAt
-
-b,
tac6hq
y-I
Giai he
b:l
f:l
2r
*
3b
:5
4r-b:3
0,75
2a)
Ggi tgadO
diem
,4 la
(rr;Ao).
Do cli6m
,4
thu6c
tryc
Oy
n€n
ro
<sub>- </sub>
0.
Do
di6m ,4
thuQc dudrng
thing
(d),A
:
n'Lr
*
4
n6n
ut:
ffine
*
4
<sub>- </sub>
m.0
*
4
<sub>- </sub>
4.
KL:
tsa d0
di6m
A
la
(0;a).
fim
cua m A.
0,75
b)
Tim
tiit
cd
gid
tr! cfia
m
AO dwong
thdng
(d)
cdt
tryc
Or
tgi
itilm B
sao cho
tam
gidc
OAB
ld
tam gidc cfrn.
(*utrr).
oo
di6m
B
thuQc
tryc
or
ndn
<sub>vo </sub>
-
0.
Vi
di6m
B
thuQc ducmg theng
<sub>(d),y -- </sub>
rrln
+ 4
dan d6n 0
<sub>- </sub>
mna
*
4
Yt
m*O
+
nB:a
*
OB
-prl
<sub>- </sub>
l#l
Vi
A
OB
<sub>- </sub>
900 n€nclOtam giitc
OAB ldtam
gitrccdnthi OA
<sub>- </sub>
OB. Md
OA:4
n€n
OB
<sub>- </sub>
4.
KL:m-l
Ggi tga <t0 cli6m
B
le
m-l
m--l
m--L
Giai phuong
trinh:
-
<sub>l=l </sub>
<sub>- </sub>
4
e..
*
<sub>[</sub>
l*l
t
BNi
III
^
.
-.;
./,)
drcm
2b)
BNi
IV
a
00(
rl(
1r0
l)
Chirng
minh
trb
gitic
BHEK
ld ttb
gitic
nQi tiiip.
2
Di6rr
D6p
6n
Bei
Y
)
</div>
<span class='text_page_counter'>(3)</span><div class='page_container' data-page=3>
Chtmg minh
dugc
BHE
<sub>- </sub>
900 vir
Suy
ra BHE
+
BKE
<sub>- </sub>
1800.
Lap luan d6n Aen
fr
giAc
BHEK
la
ffi
^, ,.i
grac nQl trep.
BKE
:
900.
A
H
E
F
lr0
2)
Ap
dgng he
thftc
lugng
cho
L,AEB
vu6ng
tqi
E, dulng
cao
EH
c6:
BH,BA
_
BE2.
Chtmg minh tuong
tg
c6:
BK.BC
:
BE2.
Y$Y
BH,BA
:
BK,BC,
Chftng
minh
BH.BA:
BK.BC.
lr0
3)
-
-^
chtmg
minh
dusc
BHK
<sub>- </sub>
BEK (l).
(
BHBK
le
tf
gitrc nQi ti6p)
Chimg minh
dugc
BEK
:
BCE
(2). (Cung phU
voi EBC
)
Chimg minh
dusc
frE
<sub>- ffi </sub>
(3). (
BCEF
la
tri
gitcnQi ti6p)
^
^
chimg
minh
dusc
HFE
<sub>- FHI </sub>
(4).
(tam giitc
FHI
c6n
tai /.
<sub>)</sub>
Ttr
(
l),(2),(3),
(4)
suy
ra
ffiK
-frt.
Do
A.ABCnhqn,
hai
di6m
I
vd
K
nim
ctrng phia AOi vOi
duong
thing
HF
n6n
I/,
I,
K li
ba
ili6m
thing hing.
hdng.
Ch*ng
minh
ba 'm H
,I,K
ld
ba th
3,0 diam
0r5
Bni
v
0,5 diam
Gidiphwongtrinh
J"
+,h.
1-
12
*!
Lap luan dan Aen
r
<sub>- </sub>
|
(thoa mfrn
DKXD).
KL:
phuong
trinh
co nghiQm duy ntr6t
lir
r
<sub>- </sub>
1.
-0.
3r
<sub>-2 -l</sub>
,
+
zJr +z
3r
<sub>-2 </sub>
<sub>-2r2 </sub>
*2
3r
<sub>-2 - </sub>
12
+L
.
.
<+,(* -r)'
*
(.6-
r)'
*
(
2
DKXD:
r
)
<sub>-3</sub>
<sub>-.</sub>
Ji+
Luu
<sub>f:.c6c </sub>
c6ch
ldm kh6c n6u
dring
hqc sinh v6n tluqc di6m tuong img
vdi
bitiu ditim
cria
ddn ch6m.
uong
H
J
Di6m
Ddp
6n
Bii
f
K
2
3
a
,(
,
/
o
</div>
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