According to the Triangle inequality theorem, this does not work
For a triangle to be valid, the length of any two sides added together must by greater than the length than the third side.
In this example, we can see that the side with length 1 added to the side with length 2 is equal to 3inches.
3 inches is less that 4inches (the length of the 3rd side). So that triangle does not work.
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Answer
This triangle does not work, because the sum of the lengths of any two sides of a triangle is NOT greater than the length of the third side.