Abc, bc, ac, ab, A, B and C are all integers of at least 1

There are 7 * * * items in total, and 7 integers with at least 1 add up to 7. There is only one case, that is, all seven are 1.

That is, abc=bc=ac=ab=a=b=c= 1, which is an equilateral triangle with a side length of 1.

Area, using the formula, let the included angle c between side A and side B be (absinC)/2.

In this problem, it is an equilateral triangle, the angle is of course 60, a= 1=b= 1, so the area is (SIN 60)/2, that is, a quarter of the root number is 3.