Definition:Euclid's Definitions - Book I/20 - Triangles by Sides
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Definition
As Euclid defined it:
- Of trilateral figures, an equilateral triangle is that which has its three sides equal, an isosceles triangle that which has two of its sides alone equal, and a scalene triangle that which has its three sides unequal.
(The Elements: Book I: Definition $20$)
