Yes.
The triangle inequality theorem states that a triangle is possible if the sum of two sides is larger than the 3rd side.
In this case, the sides are 4, 5 and 6.
4+5 is bigger than 6
4 + 6 is bigger than 5
5 + 6 is bigger than 4.
The sum of any 2 sides is always larger than the 3rd side, so this triangle is possible.
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Answer: Yes