(1) ++ =0, ++ =0 2+2+2 =0, 2 + 2 + 2 =0

2 + 2 + 2 =0

+ + =0    2 :

2 + 2 + 2 = 0 

2 +  2 + 2 = 0 ----(1)

+ + =0    2 :

2 + 2 + 2 = 0

2 + 2 + 2 = 0 ----(2)

+ + =0    2 :

2 + 2 + 2 = 0

2 + 2 + 2 = 0-----(3)

(1) (2) (3) + + =180 + = 180 ( + ) =

2 + 2 + 2 + 2 + 2 + 2 + 2 + 2 + 2 = 0

2 + 2 + 2 + 2( + ) +  2( + ) + 2( + ) = 0

2 + 2 + 2 + 2( + ) + 2(+ ) + 2( + ) = 0

2 + 2 + 2 + 2 + 2 + 2 = 0

2 + 2 + 2 +  2( + + ) = 0

2 + 2 + 2 + 2 = 0

2 + 2 + 2 = 0


  2 + 2 + 2 = 0

+ + =0 + + =0

:

2 + + = 0 ----(1) --------- 2 + + = 0 ---(2)

+ 2 + = 0 --(3) -------- + 2 + = 0 ---(4)

+ + 2 = 0 ---(5)-----  + + 2 = 0---(6)

(1) (2) 2 2 = 2

2 2 +    +    = 0

2 2(+) + ( + ) =0 

2 - - =0 ---------------(7)

2 - - = 0  (3) (4) -----(8)

2 - - = 0 (5) (6) -----(9)

(7) (8) (9) + + = 180 + = 180 ( + ) = -

2 + 2 + 2 - 2 - 2 - 2 =0

2 + 2 + 2 - 2( + + ) = 0 

2 + 2 + 2 - 2 = 0 

2 + 2 + 2 = 0  : ( + + )2 ( + + )2