A ASBB C′ = B H BC ′ 2 SBB C= A
2 .
a a
S
BB C
′
= B H BC ′ 2 S
BB C
= a .
=
3
3
LT
.
ABC
V = B H S ′ 2 .
2
3
4
2
1
= a
3
3
= = 1 .
3
3
V
′ ′
= V
′ ′
1 2 1
2 3 . V
LT
3 V
LT
.
.
A CC B
2
A CC B B
BB C
′
BB C
3
LT
ABC
2
3
3
′ ′
′ ′
LT
LT
.
.
A CC B
A CC B B