We know the angle of the greatest side is greatest,

SO ,\(\angle ABC > \angle BAC > \angle ACB\)

Now the triangle cannot be equilateral as all sides are not equal.

therefore \(\angle ACB\)cannot be 60°

If \(\angle ACB\)= 61°

then \(\angle BAC + \angle ABC\) = 119°, but this cannot be possible because either angle cannot be \(<\)then \(\angle ACB\)

Therefore \(\angle ACB <\) 60°