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标题: 正三角形的威力4 - A question [打印本页]

作者: yma16 时间: 2005-8-27 07:16
标题: 正三角形的威力4 - A question

Hi All,

In the link, why is O on AD?

http://www.topchinesenews.com/listo.aspx?topic_id=9&msg_id=3612&level_string=0z02&page=6

Thanks.

作者: husonghu 时间: 2005-8-27 07:49
标题: 我试着回答。

On segment AD, find point O, so that OC=OD;
then also we have www.ddhw.com

作者: 寒潭清 时间: 2005-8-27 09:39
标题: 同意HH [@};-][>:D<]

同意HH

作者: yma16 时间: 2005-8-27 18:40
标题: 回复：我试着回答。

Your statements are true. But it seems that you got O is the center because www.ddhw.com

作者: husonghu 时间: 2005-8-28 00:26
标题: What you said is true. But what we care here is...

whether or not you can draw a circle with point O as the center and with the three points, C, D, B, on the circle.

What I tried to answer is: We do can draw such a circle, or, such a circle does exist.

www.ddhw.com

作者: husonghu 时间: 2005-8-28 00:58
标题: No, actually you got something mixed up. See,...

you not only need to find the point O, but also, more importantly, you need to make sure that OC=OD, which is the radius of the circle.

In your statement, although "O can move on this circle and

So, there is one, and only one, point O on segment AD, from which you can draw a cirlce with radius OD (or OC) that passes all the three points: C, D, B.

Hope this helps.

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