A triangle has sides with lengths: 4, 12, and 2. How do you find the area of the triangle using Heron's formula?
No such triangle is possible since no triangle can have a side which is longer than the sum of the other two sides (at least in Euclidean space)
If you attempted to apply Heron's formula:
for a triangle with sides
you would end up attempting to find the square root of a negative number: