If a,b,c are the sides of a triangle, and $$a^2 + b^2 +c^2 = bc + ca + ab$$, then the triangle is:
$$(a+b+c)^2 = a^2 + b^2 + c^2 + 2(ab + bc + ca) => 3(a^2 + b^2 + c^2)$$
This is possible only if a = b = c.
So, the triangle is an equilateral triangle.
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