内容正文:
书
(2)
!"#$%#
8
!&
,
'($
NMJH
)*!+
;
(3)
!"#$%#
8
!&
,
'($
SPQR
)*!+
.
21.
,-./
,
0
118×200×34+75×160×
1
2+
118×a10×200×(1-
3
4)+(75-3a)×160×(1-
1
2)≥32500.
10
a≥8.
2
:a
3456*
8.
22.(1)
7*∠A=90°,∠C=60°,!8∠ABC+
∠ADC=360°-∠A-∠C=210°.7* ∠EDC9
∠ABC3:;<=>? P,!8 ∠PBC= 12∠ABC,
∠PDC= 12∠EDC.,-@A$3BA9CD,0
∠BPD=∠PBC+∠C-∠PDC= 12∠ABC+60°-
1
2∠EDC=
1
2∠ABC+60°-
1
2(180°-∠ADC)=
1
2(∠ABC+∠ADC)-30°=75°.
(2)DG
E
BH
F:G
.
DH%I
:
J?
B
K∠ABC3:;<=DG>?M,#L.7
*
BM,BH
;MN ∠ABC,∠CBF3:;<,!8
∠MBC= 12∠ABC,∠CBH=
1
2∠CBF.!8 ∠MBH
= ∠MBC +∠CBH = 12∠ABC +
1
2∠CBF =
1
2(∠ABC+∠CBF)=90°.H(1)3OP,0∠DMB
=75°.
!8∠DMB≠∠MBH.!8DGEBHF:G.
!"#$%&''()*+,-./
(
%
)
0
、
!"
1 2 3 4 5 6 7 8 9 101112
#$
B B C C C D B A B D B C
%
、13.5; 14.60; 15.105; 16.120.
1
、17.(1) x=2,
y=-1{ ; (2)x<3.
18.
1FQRS
x-1
2 >x-3,
2(x-3)≤x-4
{
,
0
x≤2.1T
U
1+x=m,
0
x=m-1.
!8
m-1≤2.10m≤3.
19.
7*∠B=30°,∠BDA=130°,!8∠BAD=
180°-∠B-∠BDA=20°.7*ADN∠BAC3:;
<
,
!8∠BAC=2∠BAD=40°.!8∠ACB=180°-
∠B-∠BAC=110°.7* CEN AB(V3W,!8
∠AEC=90°.!8∠ACE=90°-∠EAC=50°.
20.(1)
X5YZ[3\]*
xm/min,̂
5_Z
[3\]*
5
3xm/min.
,-./
,
0
5×53x-5x=400.
10
x=120.̀
ab
,
cd./
.
!8
5
3x=200.
2
:
5_Z[3\]N
200m/min,
5YZ[3\
]N
120m/min.
(2)
X
ymin
e5_fgE5Yhi
.
,-./
,
0
120y+200y=400.
10
y= 54.̀ ab,cd./.
2
:
5
4mine5_fgE5Yhi.
21.(1)
Xjk
A
lmno
x
p
,
jk
B
lmno
y
p
.
,-./
,
0
3x+2y=55,
6x+5y=130{ .10 x=5,y=20{ .
2
:
jk
A
lmno
5
p
,
jk
B
lmno
20
p
.
(2)
Xqr
A
lmno
m
k
,̂
qr
B
lmno
(50-m)
k
.
,-./
,
0
5m+20(50-m)≥850.10m≤10.
2
:A
lmno4stqr
10
k
.
(3)
7*5uvwxqr
A
lmno
8
k
,
4st
qr
10
k
,
!8
8≤m≤10.
7*
m
*yz{
,
!8
m
|}6*
8
~
9
~
10,
h
3
50-m
|}6*
42,41,40.
!8
3
qrT
:
T
1:
qr
A
lmno
8
k
,B
lmno
42
k
,
!
*
:5×8+20×42=880(
%
);
T
2:
qr
A
lmno
9
k
,B
lmno
41
k
,
!
*
:5×9+20×41=865(
%
);
T
3:
qr
A
lmno
10
k
,B
lmno
40
k
,
!
*
:5×10+20×40=850(
%
).
7*
880>865>850,
!8T
3
4
.
22.(1)∠BPC=90°-12∠A;
(2)①BA,CD=>?Q,#L,̂ ∠P=90°-
1
2∠Q.!8∠Q=180°-2∠P.
!8∠BAD+∠CDA=180°+∠Q=180°+180°
-2∠P=360°-2∠P.!8∠P=180°-12α.
②0°<α<180°,△BPCNA@A$;α
=180°
,△BPCNA@A$;180°<α<360°
,△BPCNA@A$.
!"#$%&'