内容正文:
3456789
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11.1
+(,-./012
11.1.1
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1.C 2.C 3.B 4.C 5.D 6.C 7.5 8.1<a<4 9.4<BC≤ 83槡3 10.D
11.A 12.8
4?@ABC
13.B 14.C 15.C 16.1cm<x<7cm,3cm
ý
5cm,2,2cm
ý
4cm,6cm,3
17.
¬
:
Â!0?��
,|a-4|≥0 (b-9)2≥0.�|a-4|+(b-9)2=0,
∴|a-4|=0,(b-9)2=0
H
a=4,b=9.
D
a
3�8
,
HQ#�83
4,
«
3
4+4<9,
pJ¬�s%56%79
;
D
b
3�8
,
Hh4d�%56
þ83
9+9+4=22.
DEFGHI
18.
¬
:(1)1 4 10 (2)3×2×16
4×3×2
6
5×4×3
6
n(n-1)(n-2)
6
(3)
y�wê
n
4|
,
ë¬t�#?��w9%|IJ�×#4%56
,
C
µ#4|
A
ê
n
$Cà
,
Cµ$4|
B
ê
(n-1)
$Cà
,
Cµ%4|
C
ê
(n-2)
$Cà
,
pJ#%ê
n(n-1)(n-2)
4%56
,
·△ABC,△ACB,
△BAC,△BCA,△CBA,△CAB: � # 4 % 5 6,̧ â � J 6,õ Sn
=n(n-1)(n-2)6 .
19.(1)∵|b+c-2a|+(b+c-5)2=0,∴b+c-2a=0
ì
b+c-5=0,∴2a=
5,
¬*
a=52.
(2)∵|b+c-2a|+(b+c-5)=0,∴b+c-2a=0
ì
b+c-5=0,
Â
b+c
-5=0,
*
c=5-b.
(3)
Â%569%79
,
*Î
5-b≥ 52,õ b≤
5
2Ú,
b<5-b+52
b+52>5-
{ b,
∴ 54<b≤
5
2;Î5-b<
5
2,õb>
5
2Ú,
5-b+52>b
5
2-(5-b)<
{ b,∴ 52<b<154,
∴b
9CK�\3
5
4<b<
15
4.
11.1.2
(,-0J
、
K1+,LM1N(,-0OPQ
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1
0|
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2
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3
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4
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1.A 2.B 3.C 4.C 5.A
6.D 7.A 8.D 9.①②③ 10.º
4?@ABC
11.D 12.A 13.B 14.A
15.∵AD、BE
:△ABC9x,∴S△ABC=
1
2BC·AD=
1
2AC·BE,∴BC·AD=
AC·BE,∵BC=5cm,AD=6cm,AC=7cm,∴BE=5×67 =
30
7cm
DEFGHI
16.
¬
:(1)
;<pq
. (2)
«3
CM
:△ABC7ABw9
0�
,
pJ△AMCn△BMCd`(AM=BM)�x
(CD),̀
<�¶Zd
,̧ S△AMC=
1
2S△ABC=
1
2×40=
20. (3)
«3△AMC9�¶312,pJ△ABC9�
¶3
24.
pJ
1
2×AB×4=24.̧ AB=12.
17.(1)65 (2)1∶4 (3)43ý
22
3 ①Î Pt ACwÚ,∵△BCP9�¶ =
18,∴ 12×9×CP=18,∴CP=4,∵3t=4,t=
4
3. ②Î Pt ABwÚ,∵
△BCP=18,
S△BCP
S△ABC
= 1812×9÷2=
1
3,∴BP=
1
3AB=5,∴AP=15-5=10,∴
3t=12+10=22,t=223,̧ t=
4
3ý
22
3Ú,S△BCP=18.
11.2.
+(,-./0,
11.2.1
(,-0R,
456789
1.180° 2.
»¾
»¾
3.40° 60° 80°
4:;<=>
1.D 2.D 3.C 4.C 5.B 6.20° 7.360° 8.C 9.C 10.B 11.A 12.A
4?@ABC
13.29° 14.B 15.C 16.D
17.
Â!ÿ
,
*∠NBA=45°,∠NBC=75°,∴∠ABC=∠NBC-∠NBA=30°.∵
BN∥AS,∴∠BAS=∠NBA=45°.∠ABC+∠BAC+∠ACB=180°,∠ACB=
75°,∠ABC=30°,∴∠BAC=75°,∴∠SAC=∠BAC-∠BAS=75°-45°=
30°.∴
¼`m
A
Z�oe
30°
]c½c¾l
C
p