I was said that a geometrical method is very useful to solve problems. Do you have any idea? Any book can you suggest me to read?

Thanks.

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- April 3rd 2011, 04:48 AMLuyenTDHGeometrical method
I was said that a geometrical method is very useful to solve problems. Do you have any idea? Any book can you suggest me to read?

Thanks. - April 3rd 2011, 05:18 AMveileen
Well, if "geometrical" includes trigonometry and vectors I have some problems that can be solved easier like that. Also geometrical method is useful in problems with complex numbers (and, yes, I have problems that can be solved easier that way too).

Books - um, a good and complet one that I know is "Complex numbers from A to Z" - Titu Andreescu, Dorin Andrica. - April 3rd 2011, 05:33 AMLuyenTDHGeometrical methods
Thanks for Veileen's soon comments.

By chance, do you know about the Titu's lemma? - April 3rd 2011, 05:39 AMveileen
"Titu's lemma" Do you refer at that lemma that can be deduced from Cauchy's inequality? If so, yes, I know ^^

- April 3rd 2011, 05:51 AMLuyenTDHTitu's lemma
- April 3rd 2011, 06:06 AMveileen

Equality if and only if

Demonstration:

(Cauchy's inequality)

Let and , then:

which is exactly Titu's inequality.