 SC = =     V V V SM SN SP SN1 1 1 1 2 2 2 7=  + =  + =  + =

4

.

SN

7

ST

=

4

2

10

5

.

SC

=

=

V

V

V

SM SN

SP SN

1

1

1 1 2

2 2

7

=

+

=

+

=

+

=

.

.

.

S AMNP

S AMN

S ANP

.

.

.

.

.

2

2

2 2 5

5 3

30

V

S

V

SB SC

SD SC

S ABCD

S ACB

S ACD

7

23

20

30

.

V

=

V

V

= −

V

V

=

V

ABCD AMNP

S ABCD

S AMNP