x = aabb ab cd dc ba p q r 3 3 3 a ld a md a nd m n n l l m 0 p q r 3 3 3 l m n pqr 3 ab a n n n 2 2 1 1 1 1 - - - 2 n 2 ab a n 1 2 3 n 2 n 10 1 10 1 4 4 n n a - - a k 2 3 2k 10 1 10 1 10 1 10 1 10 1 10 1 8 4 8 8 8 4 k k - - - - - - a k 1 2 2k 1 10 1 10 1 10 1 10 1 10 1 10 1 4 2 1 4 2 2 1 2 2 2 1 2 ( ) ( ) ( ) k k k + + + - - - - + - 0 k k k n k 0 k n 2 2 n 3 AC = 2cos 2 7 BD = 2cos 3 7 2 p m m n p 2 m m n 2 + + 2m 1 p m m n 2 + + m - + - 3 12 3 6 3 n n n 3 k n 2 k k n 2 k k a b ab 2 2 1 + + a a kb 2 aa b k 3 2 a a b k a b a a a 2 2 2 1 1 - - -
