Geometry Marathon v1.0

For discussing Olympiad level Geometry Problems
tushar7
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Re: Geometry Marathon v1.0

Unread post by tushar7 » Thu Dec 09, 2010 10:11 pm

i didnt get what you(zzz) meant by whoever can post any problems .
So this wont just be geometry marathon?!

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Moon
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Re: Geometry Marathon v1.0

Unread post by Moon » Thu Dec 09, 2010 10:55 pm

Can't anyone solve Problem 4?? It is easy I guess. :)

Anyway, I shall post problem in January, now this month. Sorry...
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Zzzz
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Re: Geometry Marathon v1.0

Unread post by Zzzz » Fri Dec 10, 2010 5:18 am

tushar7 wrote:i didnt get what you(zzz) meant by whoever can post any problems .
So this wont just be geometry marathon?!
Anyone can post any gemotry problem here:)
Every logical solution to a problem has its own beauty.
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TIUrmi
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Re: Geometry Marathon v1.0

Unread post by TIUrmi » Fri Dec 10, 2010 1:33 pm

Couldn't solve Problem 4 using transformation. :( An appreciable fact is found out but proof isn't complete.
However, I am posting another problem.

Problem 5:
Line $l$ is tangent to the circumcircle of acute triangle $\triangle ABC$ at $B$. Let $K$ be the projection of the orthocenter of $\triangle ABC$ onto line $l$, and let $L$ be the midpoint of $AC$. Show that $\triangle BKL$ is isosceles.

Someone explain me what does 'projection on the orthocenter of triangle ABC onto line l' mean.

Check the question I added before question 3. Help me by proving if it's true or disprove if it's false.

If projection means reflection the question is incorrect. But I guess it doesn't.
"Go down deep enough into anything and you will find mathematics." ~Dean Schlicter

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Moon
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Re: Geometry Marathon v1.0

Unread post by Moon » Fri Dec 10, 2010 3:55 pm

Please don't post new problem before someone solves the previous one. Unless, the problem is unsolvable. We can also set some rule:
If the problem goes unsolved for two days the poster of the problem will post a solution, and then anyone may post a new problem. In case the person who posted the problem is not available the problem must be tagged as [UNSOLVED] and then anyone may post a new problem. :)
"Inspiration is needed in geometry, just as much as in poetry." -- Aleksandr Pushkin

Please install LaTeX fonts in your PC for better looking equations,
learn how to write equations, and don't forget to read Forum Guide and Rules.

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TIUrmi
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Re: Geometry Marathon v1.0

Unread post by TIUrmi » Sat Dec 11, 2010 10:14 am

Please please reply the two questions in coloured font. @Admin or anybody who can.
"Go down deep enough into anything and you will find mathematics." ~Dean Schlicter

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Zzzz
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Re: Geometry Marathon v1.0

Unread post by Zzzz » Sat Dec 11, 2010 1:36 pm

TIUrmi wrote:Please please reply the two questions in coloured font. @Admin or anybody who can.
Cabri II says $P,Q$ and $R$ are collinear in problem 1 ! But I couldn't prove it.. :x
Every logical solution to a problem has its own beauty.
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TIUrmi
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Re: Geometry Marathon v1.0

Unread post by TIUrmi » Sat Dec 11, 2010 6:57 pm

My proving used that fact but I could prove this part.
"Go down deep enough into anything and you will find mathematics." ~Dean Schlicter

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Moon
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Re: Geometry Marathon v1.0

Unread post by Moon » Sat Dec 11, 2010 9:29 pm

Uh...I feel you guys are really stuck. :(
Projection meant perpendicular projection I guess.
"Inspiration is needed in geometry, just as much as in poetry." -- Aleksandr Pushkin

Please install LaTeX fonts in your PC for better looking equations,
learn how to write equations, and don't forget to read Forum Guide and Rules.

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Moon
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Re: Geometry Marathon v1.0

Unread post by Moon » Tue Dec 14, 2010 12:04 am

Should I close this marathon?
"Inspiration is needed in geometry, just as much as in poetry." -- Aleksandr Pushkin

Please install LaTeX fonts in your PC for better looking equations,
learn how to write equations, and don't forget to read Forum Guide and Rules.

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