D=50, C=150

It is definitely not an elementary school problem. I will post a solution if there is enough interest.

所有跟帖： 

• 你这个和没意思答案一样。 -兄贵- ♂ (0 bytes) () 07/30/2013 postreply 12:40:08

• 推导就不用了，给个公式就行。第2题，你算出来了吗？ -兄贵- ♂ (0 bytes) () 07/30/2013 postreply 12:41:30

• The relation between all these angles is nonlinear, in general. -BeLe- ♀ (90 bytes) () 07/30/2013 postreply 12:49:53

• 谢谢，非线性公式也行。 -兄贵- ♂ (0 bytes) () 07/30/2013 postreply 12:53:25

• It is a trig relation. -BeLe- ♀ (0 bytes) () 07/30/2013 postreply 12:55:55

• special angles很多，不止2个 -没意思说过去- ♂ (206 bytes) () 07/30/2013 postreply 15:09:17