Answer: No it can't
You can prove this with Pythagorean theorem. (a^2+b^2=c^2) In this case, 6 is the highest number so we know it has to be the hypotenuse. So plug it into the equation, 1^2+1^2=6^2, and simplify. You will get 2=36, and we know that is not true, so a triangle can't have the lengths of 1, 1, and 6.
Hope this helped you!
