math trigonometry

設 A = B - d，C = B + d，
則 (B - d) + B + (B + d) = 180 => B = 60

cos C + cos A = root 3
cos (60 + d) + cos (60 - d) = root 3
2 cos 60 cos d = root 3
cos d = root 3
d 無解
=> b 無解

我覺得 邊b的值 can be any real munber -.-

如果用呢1題黎睇嘅話...

2014-05-16 23:11:06 補充：
寫慣左 can be any real munber tim....
負數唔計 -.-

題目有問題...................