有一隻旋轉橢圓體的西瓜，長半徑為Ａ，旋轉半徑為Ｂ...

XY麵,橢圓方程:X^2/A^2+Y^2/B^2=1,切點(X,Y)
方柱體的體積V=2X*Y^2=2X*B^2(1-X^2/A^2)=2X*B^2-2B^2/A^2*X^3
V'=2B^2-6B^2/A^2*X^2=0,得X=(SQUT3)/3*A
在離中心(SQUT3)/3*A處倆頭下刀.再在圓切口,按正方切可也.
別忘了給我留塊西瓜.

所有跟帖： 

• 回複: 如果你把西瓜的中心定為原點，那麽柱體的體積。。 -NaCl- ♂ (40 bytes) () 09/12/2010 postreply 19:06:07

• 應是V=2x*(squat2*y)^2=4x*y^2,您也...不影響答案. -jinjing- ♀ (247 bytes) () 09/12/2010 postreply 19:47:11

• 回複：又想了想。 -NaCl- ♂ (217 bytes) () 09/12/2010 postreply 20:19:50

• 留下PI*A*B^2-V,很小.讓A=B,您就知道與B無關了. -jinjing- ♀ (22 bytes) () 09/12/2010 postreply 21:41:05

• 留下(4/3)PI*A*B^2-V,留下2SQUT3)/3PI=36.75% -jinjing- ♀ (24 bytes) () 09/13/2010 postreply 06:28:03

• 回複：Thanks for your explanation. I understand now. -NaCl- ♂ (131 bytes) () 09/13/2010 postreply 07:06:14

• certainly,but we have to know if x+y+z=n ,when x=y=z, -jinjing- ♀ (277 bytes) () 09/13/2010 postreply 12:04:48

• This is a wonderful method. -皆兄弟也- ♂ (149 bytes) () 09/13/2010 postreply 15:42:19

• Thanks. Parameter Method. -jinjing- ♀ (233 bytes) () 09/13/2010 postreply 17:29:16

• Sorry,First term is not right. -jinjing- ♀ (224 bytes) () 09/13/2010 postreply 17:47:58

• 此壇真乃從龍臥虎之處也。佩服，佩服。 -NaCl- ♂ (0 bytes) () 09/13/2010 postreply 21:09:47

• Thanks,I'm not strong for some open questions. -jinjing- ♀ (59 bytes) () 09/14/2010 postreply 10:16:19

• can you transit（a1+b1x）（a2+b2x）...（an+bnx）step by step? -皆兄弟也- ♂ (0 bytes) () 09/14/2010 postreply 07:59:03

• Sorry,I could say clearly and have some carelessness. -jinjing- ♀ (774 bytes) () 09/14/2010 postreply 10:00:53

• I really appreciate your effort. -皆兄弟也- ♂ (0 bytes) () 09/14/2010 postreply 10:13:56

• For n,it seems (n-1)th equition should be delt with. -皆兄弟也- ♂ (0 bytes) () 09/14/2010 postreply 10:22:32

• really wonderful. there are no (n-1)th equition . -皆兄弟也- ♂ (259 bytes) () 09/14/2010 postreply 10:43:52

• I got this transition. but,can you show what n equations are? -皆兄弟也- ♂ (333 bytes) () 09/14/2010 postreply 08:41:16

• Thank you,you correct me the +,-.some where.Up is answer. -jinjing- ♀ (0 bytes) () 09/14/2010 postreply 10:09:35

• I got n-1 independent equations.why do you use b2+c3b3+...+cnbn? -皆兄弟也- ♂ (213 bytes) () 09/14/2010 postreply 10:11:26

• n=2,your first Q is wrong. In fact t, you can choice any (n-1) -jinjing- ♀ (113 bytes) () 09/14/2010 postreply 10:41:32

• I have realized that it is wrong. -皆兄弟也- ♂ (0 bytes) () 09/14/2010 postreply 10:53:35

• The sum of all factors should be constant(no x). -jinjing- ♀ (150 bytes) () 09/15/2010 postreply 10:20:17