locus of point $X$

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Tahmid Hasan
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locus of point $X$

Unread post by Tahmid Hasan » Mon Aug 29, 2011 10:35 pm

let $ABC$ be a triangle and $X$ a point in the interior.let $AD,BE,CF$ be cevians through $X$.find all positions of $X$ such that $\frac {AX}{DX}=\frac {BX}{EX}=\frac {CX}{FX}$.
[i was inspired of this problem from an IMO problem,a good problem to research with ratios :mrgreen: ]
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*Mahi*
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Re: locus of point $X$

Unread post by *Mahi* » Tue Aug 30, 2011 7:17 pm

The centroid is only such point.
It can be shown easily, as the three cevians divide the triangle in six parts. Then the equations between the area of the parts shows that all of them are of same area. So it must be the centroid.
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Re: locus of point $X$

Unread post by photon » Tue Aug 30, 2011 8:16 pm

i got it with similarity and showing these cevians median.
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