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**shivusuja****Member**- Registered: 2006-09-14
- Posts: 56

Please Help Me Out

Sum Of The Altitudes Of Triangle Is Less Than He The Sum Of The Sides Of The Triangle.

(ae+cf+bd < Ab+bc+cd)

Proof

I Have Tried With

Sum Of The Two Sides Is Greater Than The Third Side

Abc As Sides Of The Triangle And Ae. Bd And Cf As The Altitude.

I Got

Ae+ec>ac Bd+dc>bc Cf+af>ac

Ae+be>ab Bd+ad>ab Cf+fb>bc

Adding All I Got 2ae+2bd+2cf>ab+bc+ca

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,787

hi shivusuja

I spent ages working around the triangle inequality and got nowhere. Then I had a fresh idea.

AEC is a right angled triangle with AC as hypotenuse. So

AE < AC

Similarly, in triangle CFB

CF < BC

And finally, in triangle ABD

BD < AB

Add those up and

AE + CF + BD < AC + BC + AB

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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Thank You, Bob

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

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**shivusuja****Member**- Registered: 2006-09-14
- Posts: 56

THANKS

SO SIMPLE WHOLE DAY I WORKED OUT. THIS IS 5 MARKS QUESTION. DO I GET 5 MARKS IF I DO IN THIS WAY?

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Yes, atleast in CBSE

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

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**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,889

The harder question is, can you prove the same thing, but with medians instead of heights?

*Last edited by anonimnystefy (2013-11-18 21:02:10)*

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Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

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anonimnystefy wrote:

The harder question is, can you prove the same thing, but with medians instead of heights?

A similar question came in my test and I could not answer

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

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