Helpful lemma

nafistiham · Unread post by **nafistiham** » Thu Mar 29, 2012 11:48 pm

Wiki is sufficient for isogonal conjugate.
To get more, just google.

Niloy Da Fermat · Unread post by **Niloy Da Fermat** » Thu Mar 29, 2012 11:58 pm

nafistiham wrote:Wiki is sufficient for isogonal conjugate.
To get more, just google.

Thanks!ইন্টারনেট আমার হাতে এত ক্ষমতা দিয়েছে অথচ কিছুই ব্যবহার করি না ।

Unread post by **Phlembac Adib Hasan** » Fri Mar 30, 2012 10:14 am

nafistiham vaia wrote:$H$ এর দরকার কি ? বুঝলাম না

Well,it's actually useless.

.And @ Nafi vaia, source: own.(If you don't say it's trivial

)
And a related problem:
Let $\triangle ABC$ be an acute angled triangle and $AD,BE,CF$ are the altitudes,$H$ orthocenter.Let $M,N$ be the mid points of $BC$ and $AH$.Prove that $MN\perp EF$.

sourav das · Unread post by **sourav das** » Fri Mar 30, 2012 4:12 pm

Phlembac Adib Hasan wrote:
nafistiham vaia wrote:$H$ এর দরকার কি ? বুঝলাম না
Well,it's actually useless. .And @ Nafi vaia, source: own.(If you don't say it's trivial )
And a related problem:
Let $\triangle ABC$ be an acute angled triangle and $AD,BE,CF$ are the altitudes,$H$ orthocenter.Let $M,N$ be the mid points of $BC$ and $AH$.Prove that $MN\perp EF$.

Another good trick( or problem).

Unread post by **Phlembac Adib Hasan** » Sun Jun 03, 2012 5:50 pm

My dear lemma, here is another food for you.
http://www.matholympiad.org.bd/forum/vi ... 035#p11035
Everyone,you can use it to complete my first solution.

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