重难点14 奔驰定理与四心问题【五大题型】
1 ................................................................................................................................................3
2 !"# ................................................................................................................................................4
3 $"# ................................................................................................................................................5
4 %"# ................................................................................................................................................5
5 &"# ................................................................................................................................................6
1' ()"#
*+,-./0!1 234 567+,-.89+,:;#2<=*89>?
@A0,BC“)"”F0#GH!1IJ)"#*+,-./0!1#2*0KL%M2
NOP/21QR STUVW256)"#1XUVY8.
[\L 1
1]
^_2`[ P abABC %cL2def
2gGbAPB'bAPC'bBPC 0,
Bhia
.
j634 5k0_lCm0nopFq2rstuvwxa“ ”.34 567
+,-.89+,:;#2<=*89>?@A0,BC“)"”F0#2GH9 y0z{I.
[\L 2 )"#
1])"0|}~-.
(1)!"0|}~-.
①!"0|}
?@A/0L
!"2!"/ 2:1.
!"0-.
^_2NbABC /2L P abABC !"
.
! " n
A(x1,y1) 2 B(x2,y2) 2 C(x3,y3) 2 g b ABC 0 ! " n a
P
.
(2)$"0|}~-.
①$"0|}
?@A0L
$".
$"0-.
^_2NbABC /2L P abABC $"
.
(3)%"0|}~-.
①%"0|}
?@A@+0L
%"2%"a?@A%0".
%"0-.
^_2NbABC /2?@A0%"N-.
rN02L P ab
ABC %"
.
(4)&"0|}~-.
①&"0|}
?@A/$0L
&"2&"a&0"2&"?@AL0
F.
&"0-.
^_2NbABC /2L P abABC &"
.
2]?@A0)"( 0
(1)O *bABC 0!"
.
(2)O *bABC 0$"
.
(3)O *bABC 0%"
.
(4)O *bABC 0&"
.
1
12024 ?· ·¡P¢`[L A2B2C2P N£c+,%2𝑃𝑄=
1
3𝑃𝐴2𝑄𝑅=
1
3𝑄𝐵2𝑅𝑃=
1
3
𝑅𝐶2g𝑆△𝐴𝐵𝐶:𝑆△𝑃𝐵𝐶6 ¢
A]14∶3
B]19∶4
C]24∶5
D]29∶6
¤ 1-123-24 c¥·¦§¨©·ª«¢`[𝑂a △𝐴𝐵𝐶%cL2def3𝑂𝐴+4𝑂𝐵+5𝑂𝐶= 2𝐴𝐵+3𝐵𝐶
+ 𝐶𝐴2g
𝑆△𝐴𝑂𝐵
𝑆△𝐴𝐵𝐶= ¢
A]
2
5
B]
1
4
C]
3
4
D]
3
5
¤ 1-223-24 c¥·¬·ª/¢
`[𝑂* △𝐴𝐵𝐶%0cL2 △𝐵𝑂𝐶2 △𝐴𝑂𝐶2 △𝐴𝑂𝐵
0,B®a𝑆𝐴2𝑆𝐵2𝑆𝐶2g𝑆𝐴⋅𝑂𝐴+ 𝑆𝐵⋅𝑂𝐵+ 𝑆𝐶⋅𝑂𝐶= 0.“ ”*+,-./c4¯°±²0³´2
µa34 5k0_A(“”¶m0 logo pFq2·Al¸x=a“ ”.𝑂a?@A𝐴𝐵𝐶%c
L2def
𝑂𝐴+2𝑂𝐵+3𝑂𝐶= 3𝐴𝐵+2𝐵𝐶+ 𝐶𝐴2g
𝑆△𝐴𝑂𝐵
𝑆△𝐴𝐵𝐶= ¢
A]
2
5
B]
1
2
C]
1
6
D]
1
3
¤ 1-323-24 ?·¹¨¨º·ª/¢
`[𝑂*𝛥𝐴𝐵𝐶%0cL2𝛥𝐵𝑂𝐶2𝛥𝐴𝑂𝐶2𝛥𝐴𝑂𝐵0
,B®a𝑆𝐴2𝑆𝐵2𝑆𝐶2g𝑆𝐴⋅𝑂𝐴+ 𝑆𝐵⋅𝑂𝐵+ 𝑆𝐶⋅𝑂𝐶= 0]“ ”*+,-./c4¯°±²0³´2
µa34 5k0_A(“”¶mMercedes benz¢0 logo pFq2·Al¸x=a“ ”»𝑂*
¼@𝛥𝐴𝐵𝐶%0cL2𝐴2𝐵2𝐶*𝛥𝐴𝐵𝐶0?4%@2dL𝑂ef𝑂𝐴⋅𝑂𝐵= 𝑂𝐵⋅𝑂𝐶= 𝑂𝐶⋅𝑂𝐴2g½G ¢
A]sin𝐴⋅𝑂𝐴+ sin𝐵⋅𝑂𝐵+ sin𝐶⋅𝑂𝐶= 0
B]cos𝐴⋅𝑂𝐴+ cos𝐵⋅𝑂𝐵+ cos𝐶⋅𝑂𝐶= 0
C]tan𝐴⋅𝑂𝐴+ tan𝐵⋅𝑂𝐵+ tan𝐶⋅𝑂𝐶= 0
D]sin2𝐴⋅𝑂𝐴+ sin2𝐵⋅𝑂𝐵+ sin2𝐶⋅𝑂𝐶= 0
2 !"#
22024·¾¿ÀÁ·?â`[L O a △𝐴𝐵𝐶0!"2𝐴𝐶= 𝜆𝑂𝐴+𝜇𝑂𝐵2g𝜆+ 𝜇= ÄÄ¢
A]−3
B]−2
C]1
D]6
¤ 2-12024·Å§§Æ·câ`[L𝑃* △𝐴𝐵𝐶0!"2g ¢
A]𝐴𝑃=
1
6𝐴𝐵+
1
6𝐴𝐶
B]𝐴𝑃=
1
4𝐴𝐵+
1
4𝐴𝐶
C]𝐴𝑃=
2
3𝐴𝐶+
1
3𝐵𝐶
D]𝐴𝑃=
2
3𝐴𝐵+
1
3𝐵𝐶
¤ 2-223-24 c¥·)ÇÈ/·ÉÊ¡P¢`[L𝐺a △𝐴𝐵𝐶0!"2𝐷,𝐸®*𝐴𝐵,𝐴𝐶cL2𝐷,𝐺,𝐸
?LË2𝐹a𝐵𝐶0/L2»𝐴𝐹= 𝜆𝐴𝐷+𝜇𝐴𝐸2g
4
𝜆+
1
𝜇0ÌÍÎa ¢
A]6
B]7
C]
9
2
D]
27
2
¤ 2-32024 c¥·Ï·¡P¢L O * △𝐴𝐵𝐶rN+,%cL2g¥ÐÑÒÓÔ0* ¢
A]»𝑂𝐴+ 𝑂𝐵+ 𝑂𝐶= 02g O a △𝐴𝐵𝐶0!"J
B]»(𝑂𝐴+ 𝑂𝐵) ⋅𝐴𝐵= (𝑂𝐵+ 𝑂𝐶) ⋅𝐵𝐶= 02g O a △𝐴𝐵𝐶0$"J
C]»(
𝐴𝐵
|𝐴𝐵| +
𝐴𝐶
|𝐴𝐶|) ⋅𝐵𝐶= 0,
𝐵𝐴
|𝐵𝐴| ⋅
𝐵𝐶
|𝐵𝐶| =
1
22g △𝐴𝐵𝐶a?@AJ
D]»𝑂𝐴+2𝑂𝐵+3𝑂𝐶= 02g△BOC (△ABC 0,Bhia𝑆△𝐵𝑂𝐶:𝑆△𝐴𝐵𝐶= 1:6]
3 $"#
323-24 c¥·ÏÕÖ·ª/¢𝑂*+,c L2𝐴2𝐵2𝐶+,×Ë0?4L2ØL𝑃e
f𝑂𝑃= 𝑂𝐴+𝜆
𝐴𝐵
|𝐴𝐵|cos∠𝐴𝐵𝐶+
𝐴𝐶
|𝐴𝐶|cos∠𝐵𝐶𝐴2𝜆∈R2g𝑃0ÙÚc ÛÜ △𝐴𝐵𝐶0 ¢
A]&"
B]%"
C]!"
D]$"
¤ 3-123-24 c¥·¦ÖÖÝ·ª«¢`[N △𝐴𝐵𝐶/2𝑂* △𝐴𝐵𝐶0$"2L𝑃ef
3𝑂𝑃=
1
2𝑂𝐴+
1
2𝑂𝐵+2𝑂𝐶2g △𝐴𝐵𝑃0,B( △𝐴𝐵𝐶0,Bhi*
A]
2
3
B]
3
4
C]
3
5
D]
1
2
¤ 3-223-24 c¥·ÞÖ·ª/¢𝐻* △𝐴𝐵𝐶0$"2d3𝐻𝐴+4𝐻𝐵+5𝐻𝐶= 02gcos∠𝐴𝐻𝐵0Î
a ¢
A]−30
10
B]−5
5
C]−6
6
D]−70
14
¤ 3-32024 ?¥· ·¡P¢^_2`[𝑂* △𝐴𝐵𝐶0$"2d𝑂𝐴+2𝑂𝐵+3𝑂𝐶= 02gtan∠𝐵𝐴𝐶:
tan∠𝐴𝐵𝐶:tan∠𝐴𝐶𝐵6 ¢
A]1:2:3
B]1:2:4
C]2:3:4
D]2:3:6
4 %"#
42024·)Ǩ߷?â`[L P N △𝐴𝐵𝐶rN+,%2»𝑃𝐴⋅(
𝐴𝐶
|𝐴𝐶|−
𝐴𝐵
|𝐴𝐵|) = 𝑃𝐵⋅(
𝐵𝐶
|𝐵𝐶|−
𝐵𝐴
|𝐵𝐴|) = 02
gL P * △𝐴𝐵𝐶0 ¢
A]&"
B]$"
C]!"
D]%"
¤ 4-123-24 c¥·)Çà·ª«¢`[L O * △𝐴𝐵𝐶0%"2𝐴𝐵= 4,𝐴𝐶= 32𝐶𝐵= 𝜆𝐶𝐴+𝜇𝐶𝑂2
g𝜆+ 𝜇= ¢
A]
4
3
B]
5
3
C]2
D]
7
3
¤ 4-22023 ?· ·¡P¢N △𝐴𝐵𝐶/2»sin∠𝐵𝐴𝐶⋅𝑃𝐴+ sin∠𝐴𝐵𝐶⋅𝑃𝐵+ sin∠𝐴𝐶𝐵⋅𝑃𝐶=
02gL𝑃* △𝐴𝐵𝐶0 ¢
A]!"
B]%"
C]$"
D]&"
¤ 4-32024 ?· ·¡P¢N △𝐴𝐵𝐶/2|𝐴𝐵| = 22|𝐴𝐶| = 32|𝐵𝐶| = 42O * △𝐴𝐵𝐶0%"2
d𝐴𝑂= 𝜆𝐴𝐵+𝜇𝐵𝐶2g𝜆+ 𝜇= ¢
A]
9
10
B]
7
10
C]
8
9
D]
7
9
5 &"#
523-24 c¥·áâã·ª/¢𝑂a △𝐴𝐵𝐶rN+,%cL2def(𝑂𝐴+ 𝑂𝐵) ⋅𝐵𝐴= (𝑂𝐵+ 𝑂𝐶) ⋅
𝐶𝐵= (𝑂𝐶+ 𝑂𝐴) ⋅𝐴𝐶2g𝑂* △𝐴𝐵𝐶0 ¢
A]%"
B]&"
C]!"
D]$"
¤ 5-123-24 ?¥·ä·ÉÊ¡P¢N △𝐴𝐵𝐶/2𝐴𝐶= 2 72𝑂* △𝐴𝐵𝐶0&"2𝑀a𝐵𝐶0/L2
𝐴𝐵⋅𝐴𝑂= 82𝑁*𝑂𝑀å6𝑀'𝑂0æçcL2g𝐴𝑁⋅𝐵𝐶= ¢
A]3
B]6
C]7
D]9
¤ 5-22024 ?·èé·¡P¢`[𝑂a △𝐴𝐵𝐶0&"2»𝐴(0,0),𝐵(2,0),𝐴𝐶= 1,∠𝐵𝐴𝐶= 120∘,d
𝐴𝑂= 𝜆𝐴𝐵+𝜇𝐴𝐶2g𝜆+ 𝜇= ¢
A]
2
3
B]2
C]1
D]
13
6
¤ 5-32024·ê©ëì·Ãíîï¢N¼@?@A ABC /2𝐴= 60°2𝐴𝐵> 𝐴𝐶2H a △𝐴𝐵𝐶0$"2
𝐴𝐻⋅𝐴𝐶= 202O a △𝐴𝐵𝐶0&"2d𝐴𝐻⋅𝐴𝑂=
71
98|𝐴𝐻| ⋅|𝐴𝑂|2g𝐵𝐶= ¢
A]9
B]8
C]7
D]6
c'ð
1]2024· ·ñâL𝑂,𝑃* △𝐴𝐵𝐶rN+,%ò4×£0L2ef𝑂𝑃= 𝑂𝐴+ 𝑂𝐵+ 𝑂𝐶2g𝑂𝑃óÜ
△𝐴𝐵𝐶0 ¢
A]!"
B]&"
C]%"
D]$"
2]23-24 c¥·¹¨Æº·ª«¢`[𝑂* △𝐴𝐵𝐶%0cL2» △𝐵𝑂𝐶, △𝐴𝑂𝐶, △𝐴𝑂𝐵0,B®ôa
𝑆1,𝑆2,𝑆32g𝑆1 ⋅𝑂𝐴+ 𝑆2 ⋅𝑂𝐵+ 𝑆3 ⋅𝑂𝐶= 0.34 5k0_A(“”¶m0log𝑜pFq2·Al¸x=
a“ ”.^_2`[𝑂* △𝐴𝐵𝐶0$"2d𝑂𝐴+2𝑂𝐵+3𝑂𝐶= 02gtan∠𝐵𝐴𝐶:tan∠𝐴𝐵𝐶:tan∠𝐴𝐶𝐵=
¢
A]1:2:3
B]1:2:4
C]2:3:4
D]2:3:6
3]23-24 c¥·Æõö÷·ÉÊ¡P¢L P *¼@ △𝐴𝐵𝐶%cL2døN𝜆∈𝑅2ù𝐴𝑃= 𝜆(𝐴𝐵+ 𝐴𝐶)2g
¥Ðúû/2×Tüýþ △𝐴𝐵𝐶aÿ?@A0* ¢
A]L𝑃* △𝐴𝐵𝐶0$"
B]L𝑃* △𝐴𝐵𝐶0!"
C]L𝑃* △𝐴𝐵𝐶0&"
D]L𝑃* △𝐴𝐵𝐶0%"
4]2024·Æõ·?â+,G △𝐴𝐵𝐶~=%cL O2Ā^_r_A2» △𝑂𝐴𝐵2 △𝑂𝐵𝐶2 △𝑂𝐶𝐴
0,B®ôI𝑆𝑐2𝑆𝑎2𝑆𝑏2gG𝑆𝑎⋅𝑂𝐴+ 𝑆𝑏⋅𝑂𝐵+ 𝑆𝑐⋅𝑂𝐶= 0]µ_ACm0𝑙𝑜𝑔𝑜pFq2°
vā³´xa“ ”]`[ △𝐴𝐵𝐶0%@ A2B2C 05®a a2b2c2»ef𝑎⋅𝑂𝐴+𝑏⋅𝑂𝐵+𝑐⋅
𝑂𝐶= 02g O a △𝐴𝐵𝐶0 ¢
A]&"
B]%"
C]!"
D]$"
5]23-24 c¥·ÏĂă·ª/¢𝑂a △𝐴𝐵𝐶rN+,%cL2ef𝑂𝐴+2𝑂𝐵+2𝑂𝐶= 02g △𝐴𝐵𝐶0
,B( △𝐵𝑂𝐶0,B0iÎa ¢
A]6
B]
8
3
C]
12
7
D]5
6]23-24 c¥·Ąą·ª«¢“ ”µ=:;Ćq0noćĈ2*+,-./c4¯°±²
0³´.w0ĉĊ%M*
`[𝑀* △𝐴𝐵𝐶%cL2 △𝐵𝑀𝐶2 △𝐴𝑀𝐶2 △𝐴𝑀𝐵0,B®a𝑆𝐴2𝑆𝐵2𝑆𝐶2
d𝑆𝐴⋅𝑀𝐴+ 𝑆𝐵⋅𝑀𝐵+ 𝑆𝐶⋅𝑀𝐶= 0.»𝑀a △𝐴𝐵𝐶0$"23𝑀𝐴+4𝑀𝐵+5𝑀𝐶= 02gcos∠𝐴𝑀𝐵= ¢
A]−6
3
B]−6
6
C] 6
6
D] 6
3
7]23-24 ?·ê©ċº·ÉÊ¡P¢`[ △𝐴𝐵𝐶2𝐼*=%"2%@𝐴,𝐵,𝐶r50®𝑎,𝑏,𝑐2g ¢
A]𝐴𝐼=
1
3(𝐴𝐵+ 𝐴𝐶)
B]𝐴𝐼= 𝑐𝐴𝐵
𝑎+ 𝑏𝐴𝐶
𝑎
C]𝐴𝐼=
𝑏𝐴𝐵
𝑎+𝑏+𝑐+
𝑐𝐴𝐶
𝑎+𝑏+𝑐
D]𝐴𝐼= 𝑐𝐴𝐵
𝑎+𝑏+ 𝑏𝐴𝐶
𝑎+𝑐
8]23-24 c·ÆõČÞ·ª«¢𝑂a?@A%čcL2𝑎、𝑏、𝑐Ďaď6 1 0Đđ
2def𝑎𝑂𝐴+𝑏𝑂𝐵+𝑐
𝑂𝐶= 𝐶𝐵2»𝑆𝛥𝑂𝐴𝐵、𝑆𝛥𝑂𝐴𝐶、𝑆𝛥𝑂𝐵𝐶®𝛥𝑂𝐴𝐵、𝛥𝑂𝐴𝐶、𝛥𝑂𝐵𝐶0,B2g𝑆𝛥𝑂𝐴𝐵:𝑆𝛥𝑂𝐴𝐶:𝑆𝛥𝑂𝐵𝐶a ¢
A](𝑐+ 1):(𝑏−1):𝑎
B]𝑐:𝑏:𝑎
C]
1
𝑎:
1
𝑏−1:
1
𝑐+1
D]𝑐2:𝑏2:𝑎2
ñ'Ē
9]23-24 c¥·ÞÖēĔ·ÉÊ¡P¢
ĕĖėN 1765 Ęę0Ě?@A0:;ěcĜ/ĝþ
?@A0&"'!"'$"ĞğĠ6£cú2d!"&"0*!"$"0cġ2Ģ
ģxa?@A0Ėė2Ĥ gģxaĖė .L O'G'H ®*△ABC 0&"'!"'$"2
d M a BC 0/L2g ¢
A]𝑂𝐻= 𝑂𝐴+ 𝑂𝐵+ 𝑂𝐶
B]𝑆△𝐴𝐵𝐺= 𝑆△𝐵𝐶𝐺= 𝑆△𝐴𝐶𝐺
C]𝐴𝐻= 3𝑂𝑀
D]𝐴𝐵+ 𝐴𝐶= 4𝑂𝑀+2𝐻𝑀
10]23-24 c¥·ĥĦħĨ·ª/¢“ ”µ=:;Ćq0noćĈ2*+,-./c4¯
°±²0³´] (?@A)"!"、%"、&"、$"¢GHĩĪ0ī]w0ĉĊ%M*
`[𝑀
* △𝐴𝐵𝐶%cL2△𝐵𝑀𝐶,△𝐴𝑀𝐶,△𝐴𝑀𝐵0,B®a𝑆𝐴,𝑆𝐵,𝑆𝐶2d𝑆𝐴⋅𝑀𝐴+ 𝑆𝐵⋅𝑀𝐵+ 𝑆𝐶⋅𝑀𝐶=
0]s¥ĬĐĭ0G ¢
A]»𝑆𝐴:𝑆𝐵:𝑆𝐶= 1:1:12g𝑀a △𝐴𝑀𝐶0!"
B]»𝑀a △𝐴𝐵𝐶0%"2g𝐵𝐶⋅𝑀𝐴+𝐴𝐶⋅𝑀𝐵+𝐴𝐵⋅𝑀𝐶= 0
C]»𝑀a △𝐴𝐵𝐶0&"2g 𝑀𝐴+ 𝑀𝐵⋅𝐴𝐵= 𝑀𝐵+ 𝑀𝐶⋅𝐵𝐶= 𝑀𝐴+ 𝑀𝐶⋅𝐴𝐶= 0
D]»𝑀a △𝐴𝐵𝐶0$"23𝑀𝐴+4𝑀𝐵+5𝑀𝐶= 02gcos∠𝐴𝑀𝐵=
6
6
11]23-24 c¥·ÞÖēĔ·ª/¢L𝑂N △𝐴𝐵𝐶rN0+,%2 ¢
A]»ØL𝑃ef𝑂𝑃= 𝑂𝐴+𝜆
𝐴𝐵
|𝐴𝐵|sin𝐵+
𝐴𝐶
|𝐴𝐶|sin𝐶(𝜆> 0)2gØL𝑃0ÙÚc óÜ △𝐴𝐵𝐶0$"
B]»ØL𝑃ef𝑂𝑃= 𝑂𝐴+𝜆
𝐴𝐵
|𝐴𝐵|cos𝐵+
𝐴𝐶
|𝐴𝐶|cos𝐶(𝜆> 0)2gØL𝑃0ÙÚc óÜ △𝐴𝐵𝐶0!"
C]»2𝑂𝐴+ 𝑂𝐵+3𝑂𝐶= 02𝑆△𝐴𝑂𝐶2𝑆△𝐴𝐵𝐶® △𝐴𝑂𝐶2 △𝐴𝐵𝐶0,B2g𝑆△𝐴𝑂𝐶:𝑆△𝐴𝐵𝐶= 1:6
D]`[ △𝐴𝐵𝐶?4%@𝐴2𝐵2𝐶05®*𝑎2𝑏2𝑐2»𝑎⋅𝑂𝐴+𝑏⋅𝑂𝐵+𝑐⋅𝑂𝐶= 02gL𝑂a △𝐴𝐵𝐶
0%"%"¢
?'Įį
12]23-24 c· ·İıIIJ¢`[ O *+,c4 L2A2B2C *+,?4×Ë0L2ØL P
efúû𝑂𝑃= 𝑂𝐴+𝜆(
𝐴𝐵
|𝐴𝐵| +
𝐴𝐶
|𝐴𝐶|)(𝜆∈(0, + ∞))2gL P 0ÙÚc ÛÜ △𝐴𝐵𝐶0
".
13]2024·)Çà·câ`[𝐺a𝛥𝐴𝐵𝐶0!"2ÜL𝐺0(𝐴𝐵,𝐴𝐶®F6L𝑃,𝑄,»𝐴𝑃=
3
5
𝐴𝐵,g𝛥𝐴𝐵𝐶(𝛥𝐴𝑃𝑄0,Bhia
.
14]2024 c¥·)ÇijĴ·ĵĶ¢“ ”*+,-./c4¯°±²0³´2µa34 5k0_
A(“”(𝑀ercedes-Benz)0𝑙𝑜𝑔𝑜pFq2·Al¸x=a“ ¢.“ ”0%M^¥
^_2`
[𝑂* △𝐴𝐵𝐶%cL2△𝐵𝑂𝐶, △𝐴𝑂𝐶, △𝐴𝑂𝐵0,B®a𝑆𝐴,𝑆𝐵,𝑆𝐶2g𝑆𝐴⋅𝑂𝐴+ 𝑆𝐵⋅𝑂𝐵+ 𝑆𝐶⋅𝑂𝐶= 0.»𝑂
* △𝐴𝐵𝐶¼@%0cL2 𝐴,𝐵,𝐶* △𝐴𝐵𝐶0?4%@2d𝑂Lef𝑂𝐴⋅𝑂𝐵= 𝑂𝐵⋅𝑂𝐶= 𝑂𝐶⋅𝑂𝐴2g¥ÐÑ
ÒĐĭ0*
.Įķ ¢
①𝑂* △𝐴𝐵𝐶0&"J②∠𝐵𝑂𝐶+ 𝐴= πJ
③|𝑂𝐴|:|𝑂𝐵|:|𝑂𝐶| = cos𝐴:cos𝐵:cos𝐶J④tan𝐴⋅𝑂𝐴+ tan𝐵⋅𝑂𝐵+ tan𝐶⋅𝑂𝐶= 0
)'8ĸ
15]2024 ?· ·¡P¢Ĺĺ“ ”289s¥#
(1)L O a △𝐴𝐵𝐶%cL2»𝑆△𝐴𝑂𝐵:𝑆△𝐵𝑂𝐶:𝑆△𝐴𝑂𝐶= 4:3:22𝐴𝑂= 𝜆𝐴𝐵+𝜇𝐴𝐶2Yđ
𝜆C𝜇0ÎJ
(2)» O a △𝐴𝐵𝐶0&"2Ļļ
sin2𝐴𝑂𝐴+ sin2𝐵𝑂𝐵+ sin2𝐶𝑂𝐶= 0.
16]23-24 c¥·Þ§ď£·ª/¢N △𝐴𝐵𝐶/2@𝐴,𝐵,𝐶r50®a𝑎,𝑏,𝑐,𝐻* △𝐴𝐵𝐶%0cL2d
𝐴𝐻=
1
4𝐴𝐵+
1
3𝐴𝐶]
(1)»𝐻* △𝐴𝐵𝐶0$"2Ļļ
7𝑐2−7𝑏2 = 𝑎2J
(2)»𝐻* △𝐴𝐵𝐶0&"2Y∠𝐵𝐴𝐶]
17]23-24 ñ·ÏĽľ·ª/¢N𝛥𝐴𝐵𝐶/2𝐴𝐶= 22𝐵𝐶= 62∠𝐴𝐶𝐵= 60°2L O a𝛥𝐴𝐵𝐶rN+,
cL2ef𝑂𝐶= 𝑚𝑂𝐴+𝑛𝑂𝐵𝑚,𝑛∈𝑅d𝑚+ 𝑛≠1¢]
1¢Ļļ
𝐶𝑂=
𝑚
𝑚+𝑛−1𝐶𝐴+
𝑛
𝑚+𝑛−1𝐶𝐵J
2¢»L O a𝛥𝐴𝐵𝐶0!"2Y m'n 0ÎJ
3¢»L O a𝛥𝐴𝐵𝐶0&"2Y m'n 0Î]
18]23-24 c¥·¦ÖĿ¿·ª«¢Ėė*ŀď0
ĕ2*ÌĒŁ0
ĕ2łN
´'O¤Ń
'
¤Ò'ńŅ'ņŇ'ňʼnŊàGŋþŌō]1765 Ę2ĖėNł0ŎIĚ?@A0:;ě
/ŏþ2æç?@A0&"'$"C!"Ġ6£c3úģxa?@A0Ėė¢2Ģ&2&
"!"06$"!"0cġ]aĻļs³´2tuIs¥Őő
^_2L O'G'H ®a△𝐴𝐵𝐶0&"'!"'$"]
(1)YĻ
𝐺𝐴+ 𝐺𝐵+ 𝐺𝐶= 0J
(2)YĻ
𝑂𝐺=
1
3 𝑂𝐴+ 𝑂𝐵+ 𝑂𝐶J
(3)YĻ
𝑂𝐻= 𝑂𝐴+ 𝑂𝐵+ 𝑂𝐶]
①!"
?/0L2!"/ 2
1J
②$"
?ú0L2(5k$J
③&"
?ú/$0L&0"¢2&"?@AL0F]
19]23-24 c¥·Þ§·ÉÊ¡P¢ *c46?@A0:; 2w0_AAŒC¶m logo
Fq2µĢćœ.^_2P * △𝐴𝐵𝐶%0æçcL2@ A2B2C r50®a a2b2c2ŔG±²
𝑃𝐴⋅𝑆△𝑃𝐵𝐶+ 𝑃𝐵⋅𝑆△𝑃𝐴𝐶+ 𝑃𝐶⋅𝑆△𝑃𝐴𝐵= 0.
(1)» P * △𝐴𝐵𝐶0%"22𝑏= 3𝑎= 4𝑐2ŕ AP BC 6L D2Y
𝐴𝑃
𝑃𝐷J
(2)» P *¼@ △𝐴𝐵𝐶0&"2𝐴= 2𝐵2𝑃𝐵= 𝑥𝑃𝐴+𝑦𝑃𝐶2Y𝑥+ 𝑦0ŖÎŗŘ.