Equilateral Triangle     Imprimer   French version


I°) Definition of equilateral triangle

I.1°) Definition:

An equilateral triangle is a triangle whose three sides are of equal length (or isometric).

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I.2°) Construct an equilateral triangle:

Let [AB] any segment. We successively trace the circle with center A and radius AB and the circle of center B and radius AB. Let C be the intersection of these two circles.

The triangle ABC is equilateral then.

We have:  AB = AC = BC.
The three angles are equal.




II°) Properties of equilateral triangle 

In an equilateral triangle, the angles are equal and measure 60 degrees.

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In an equilateral triangle medians, heights, mediators and bisectors are the same . 

They are concurrent at a point at both center of gravity,, orthocenter , center of the circle and center of the inscribed circle of triangle ABC.







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