Answer:
5 feet
Step-by-step explanation:
By triangle inequality, the sum of lengths of any two sides has to be strictly greater than the length of the third side.
Let x feet be the length of the third side.
We have 3+x>7, x+7>3 and 3+7>x.
Solving these, we get x > 4, x > -4 and x < 10.
The solution is therefore 4 < x < 10 and the smallest whole number which satisfies the inequality is 5.
Therefore the answer is 5 feet.
