内容正文:
拓展与延伸15
立体几何中的动态问题
D
C
B
Q
P
D
C
B
ABC-ABC
AB=AA=1 P
BP=λBC+HBB,
2∈[01]u∈[0
1]
()
2=1
ABP
u=1
P-ABC
=
P
AP⊥BP
2
1
-2
P
AB⊥
ABP
A
=1BP=BC+uBB
CP=uBB
CP//BB
B
P
cC,
ABP
AB +BP+AP
P CC
ABP
V5+√2
C
ABP
2√2+1
u=1
BP=λBC+BB,
B,P=λBC
B.P//BC
P
BC
B,C/1
ABC
BC
ABC
ABC
P-ABC
B
λ=
1
BC BC
MM
MM
2
C+B
MP=HBB
MP//BB
B
P
MM
P M
AM1⊥B,CAM1⊥BB
B,C∩BB=B
AM1⊥
BB.CC
BMC
BB.CC
AM1⊥BM1
A,P⊥BP
PM
AP⊥BP
C
DAP)
ED.c
B
D
1
-2
CC
D
BB
D
BP=λBC+二BB
2
DP=λBC
DP//BC
P
DD
P
D
AC
E
AE
BE
BE⊥
ACC A
AD C
ACC A
AD⊥BE
ACC A
AD⊥AE
BE∩AE=E
BE AEC
ABE
AD⊥
ABE ABC
ABE
AB⊥AD
ABBA
AB⊥AB,
AD∩AB=A AD ABC
AB D
AB⊥
ABD
A
AB
P
AB⊥
ABP
C
B
D
B
M
B
D
两=64nXS4p×h=后55a
6
ABC-ABC
AB=BC=BB
AB⊥BC
AABB
CP=V2cc
兀
10+4v2
12+4V2
16+4V2
B
A
B
B
B
AB=BC=BB =a
AB⊥BC
AB,⊥BC
BB,⊥
ABC BC
ABC
BB⊥B,C
AB,⊥B,CAB∩BB=B,
AB,BBC
ABB A
CB,⊥
ABB A
AABB
CP=V2CC =2a
BP=\2a2-a2=a
B
a
1-4
1x2ma=
a=2
2x2+2x2+22x2+号×2x2+号2x2=12+4w5
P-ABC
18V5
M
PAC
MB⊥AP
M
313
2
△ABC
0
PO
BD⊥APD
CD
AO
BC
E
ABC
AE⊥BC
PO
185
xOP-18
3
32
2
OP=6
D9 TVd
OdV
PdV
OdV
Toq
OdV
P0d
OdV
D9Tod
oqv
5O&O87
TOd
Et=do+OV=Od=gd=Vd
EM=VO
,09IS
VOZ
9
Dav
VO
Dav
d
PA⊥BC
PA⊥BD,BC∩BD=D
BCC
BCD
BDC
BCD
PA⊥
BCD
CDc
BCD
PA⊥CD
M
PAC
MB⊥AP
M
CD
PAC
43+6-4_5
13
CoS∠PAC=I
sin∠PAC=
2×4V3×6
4
33√13
CD=AC·sin∠PAC=6×
42
ABCD-ABC D
PC⊥BD,
()
5
3√2
√3
2
D
B
0
AB AC
BC
BD⊥
ACB
P
ABC
AC=AB =BC=
89r9
ABCD-ABCD
D
9
A
B
D
C
宁
BCC B
P-AAD
4
-3
DP
AC
32
AB
PF⊥BD
PF
√5
45°
π+4V2
BCC B
P
AADD
S.AD
1
×2×2=2
2
Vr-uo=
AS.uex25
3
D
AC
H
DH
D,H⊥AC
B
D
℃
B
AC∥AC
∠D,PH≤90°
∠D,PH
DP
AC
P H
DP AC
π2
P H
tan∠D,PH=
DH
6
0<HP≤V2
tan∠DPH≥V5
HP
HP
∠D,PH≥
π一3
DP AC
D
C
K
6N
H
G
方
C
B
BD⊥
ABC F AB
FP⊥BD,
P
F
ABC
FGMNHK
G,M,N,H,K
PF⊥BD
MN
M,N
AD
CD
FGMNHK
P M
FP⊥MN
FP
P
MN
2x2x5=6
2
D
91
B
B
AP
45°
∠B,AB=45°
P
BBCC
B
P
CCDD
D
P
ABB A
ADD A
AB
AD
AB AD =2V2
P
PE⊥
ABCD
E
AE
∠PAE=45°
AE=EP=2=AP
P
A
1
1
-4
P
4V2+×2元×2=4W2+元
4
P-ABC
BC⊥
PAC PA⊥AB
PA=AB=4
E
PB
AF⊥PC
F
AC
P-AEF
2W2
3
V2
E
42
5v2
B
3
3
P-ABC
BC⊥
PAC
PA=AB=4
·AC·PA=2AC
AC2+BC2=AB2=16
S.=
2
VP-AEF =VE-PAF
1 BC
VE-PAF=32
PA
S.PAF=
PA2+AC2
E PB
1 BC
.PAF=
16 AC.BC
VE-PAF=
2
316+AC2
AC=a
BC=v16-a2
16aV16-a2
VE-PAF=
316+a2
m=a2+16≥16
VE-PAF=
6V(m-16)(32-m)
3
m
9是-可
3
3
1
f(x)=-512x2+48x-1
X=
64
8
VE-PAF
1614v2
32√2
3
D
G
B
D
C
B
ABCD-ABCD AB=AD=2
AA=4M
BB
P
MP//
AB D
P
4v2
46
D
C
E
M
D
C
B
E
BC CD DD
DA AB
EF //BD //NH
MNI/B AIIFG
MEFGHN//
AB D
P
MEFGHN
AB=AD=2
AA =4
EF HN=2
EM=MN=FG=GH=5
GM=2V2 E GM
5=25am=2x22232-9
2
AB⊥AC
BC=2 M
BC
N
AC
D
BC
△ABD
AD
BD⊥DC
A
BCD
0
D BC
NO
∠AMO+∠ADB>180°
co
cole[12)
0
B
D
△AOC
AO=1
C0=1
Icole12)
N
D
M
C
B
ABCD
BD
A-BD-C
P
AD
AC
BD
60°
△ACD
26
△BCP
3
ABCD
8元
BD⊥OA
BD⊥OC
OA∩OC=O
BD⊥
AOC
AOC
BD⊥AC
AC
BD
90°
60°
A
0A=oc=)4C=2
AC=VW2)2+(22=2
DC =2
△ACD
B
BC=2
△BCP
BC
AD
BC
h
AD//BC
BC'C
BC'C」
AD中
BC'C
AD/1
BCC
BCc
BC'C
AD
BC'C
h
D
BC'C
h
Vp-8CC =YC-BCp
22-sin60°h=2.2
26
h=
△BCP
32
32
3
.BC.h=
1,2626
2
233
ABCD
0
R=V2
4πR2=8π
ABCD-ABCD
AB 1,AA =4
DD
P
C,P⊥B,E
P
y
5+√2
BD AC
AC⊥BD
ED,⊥
到
4C c
ED⊥AC
BDC
EB D
ED
EB D
EDOBD=D
AC⊥
EBD
BEC
EB D
C4⊥BE
DC
CC,
Cq
EF,BF
C BF
BB
D,C⊥
BCC B
EF∥D,C
EF⊥BCCB,
CGC
BCC B
C,G⊥EF
BFC
BFE
FEC
BFE
FEOBF -F
CG⊥
BFE
BEC
BFE
CG⊥BE
CGC
CGA CAE
CGA CAnCG=C
B,E⊥
CGA
AG
CGA
△ACG
LB,CG+∠GC,F=∠GC,F+∠BFC→∠BCG=∠B,FC∠C,B,G=∠FCB
△CB,F~aFCB,
CB
FC=2→1
P
BG
CB
B
4G+cG+4G=2+}反=5+5
A
D
G、
E
B
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