TAM
+
AB AC < BC < AB + AC
AB BC < AC < AB + BC
AC BC < AB < AC + BC
TAM
+ AB = AC
+
+- -
+
+ nhau.
+ nhau.
mang
TAM +AB = AC = BC
+
nhau.
nhau.
0.
+ 0.
TAM +
+
+ BC2= AB2+ AC2
+
0
0
+
1)2 2)2 3)2
TAM +AB = AC
+
+
+ BC2= AB2+ AC2
+ AM = BC :
+
+ 0.
BC
A
B C
A
BC
A
C
AB
450
B
A
C
TRUNG
1/
BM = MC = BC : 2
2/
ABC.
3/
Trong
2
3
AG BG CG
AD BE CF
ABC
CAO
1/
d
2/
AH
ABC
3/
Trong
ABC.
4/
AH
B
5/
AB, AC
M
B
C
A
G
F
E
D
A
C
B
H
A
C
B
H
L
K
I
A
C
B
H
C
A
B
H
A
C
B
TRUNG
1/
d
MB = MC
2/
ABC
3/
Trong
trung tr
: OA = OB = OC
ABC.
1/
Tia Oz
2/
ABC.
3/
Trong ABC, ba
IK = IL = IM
ABC.
+
+
+
+
+
+
+
+
d
M
A
C
B
O
A
C
B
D
A
C
B
L
K
M
I
A
C
B
a
b
c
4
3
2
1
3
2
1
4
B
A
.
a // b
Suy ra:
+
+
+
a c
b c
/ /a b
/ / ba
a c
b c
/ /
/ /
a c
b c
/ /a b
1/ .
THANG
1/ AB // DC.
2/ .
THANG
1/ AB // DC.
2/ .
.
THANG
1/ AB // DC.
2/ AD = BC.
3/ .
4/ .
5/ AC = BD.
1/
2/
3/
4/
5/
c
a
b
c
a
b
b
c
a
D
C
A
B
D
A
C
B
D
C
A
B
B
A
D
C
I
B
D
C
A
