e is half-distance between two foci

e is half-distance between two foci

所有跟贴·加跟贴·新语丝读书论坛

送交者: HunHunSheng 于 2009-03-12, 14:27:53:

回答: 我根据椭圆是到固定两点之和等于常数的连续轨迹得出了椭圆方程由 HunHunSheng 于 2009-03-12, 14:24:07:

I assume e^2=a^2-b^2 but I am not sure if I can
make thi sasumtion purley based upon 椭圆是到固
定两点之和等于常数的连续轨迹.

In fact, we don't even know if major and minor axis exist before we get the equation first.

So it is a chicken and egg problem

e^2=a^2-b^2 is not an asumption, it is derived from 椭圆是到固定两点之和 - chouqilozi (43 bytes) 2009-03-12, 14:38:45 (305828)
- How do you derive it? (无内容) - HunHunSheng (0 bytes) 2009-03-12, 14:44:58 (305831)
  - here - chouqilozi (357 bytes) 2009-03-12, 14:53:19 (305841)
    - the triangle is messed up. when the point is in the middle of the two focal - chouqilozi (64 bytes) 2009-03-12, 14:56:14 (305847)
    - 最后两行假设了对称性。可是你凭什么可以假设对称？ (无内容) - HunHunSheng (0 bytes) 2009-03-12, 14:55:35 (305846)
      - Didn't assume, because - chouqilozi (108 bytes) 2009-03-12, 14:58:15 (305851)
        
        那你怎么知道轨迹会和两个焦点在一条直线上？ (无内容) - HunHunSheng (0 bytes) 2009-03-12, 15:12:48 (305860)
        
        昏君you lost me. (无内容) - chouqilozi (0 bytes) 2009-03-12, 15:18:59 (305874)