## Primary Geo

For students upto class 5 (age upto 12)
sakibtanvir
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### Primary Geo

Consider, $O$ is a point inside $\triangle ABC$.Prove that, $AB+AC>BO+CO$ .
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nafistiham
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### Re: Primary Geo

priamary geo.png (90.54 KiB) Viewed 829 times
let us draw the ext. of $CO$, which intersects $AB$ at $D$
now, as we know summation of two sides of a triangle is greater than the third,
in $\triangle ACD$, $AC+AD>CD$
in $\triangle BOD$, $BD+OD>BO$
summing these two we can say,
$AC+AD+BD+OD>CD+BO$
$\Rightarrow AC+AB+OD>BO+CO+OD$
$\Rightarrow AC+AB>BO+CO$
$\sum_{k=0}^{n-1}e^{\frac{2 \pi i k}{n}}=0$
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