(a-b-c)x(b-c-a)x(c-a-b)=
(a−b−c)⋅(b−c−a)⋅(c−a−b)=c3−b⋅c2−a⋅c2−b2⋅c+2⋅a⋅b⋅c−a2⋅c+b3−a⋅b2−a2⋅b+a3
online calculator: Use the function expand((a-b-c)*(b-c-a)*(c-a-b))