the triangle is messed up. when the point is in the middle of the two focal
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送交者: chouqilozi 于 2009-03-12, 14:56:14:
回答: here 由 chouqilozi 于 2009-03-12, 14:53:19:
points, we have a'^2=b^2+e^2, where b is the height, but 2a'=2a.
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