#### Answer

If a = 4.7, b = 2.3, and c = 7.0, then triangle ABC can not exist.

#### Work Step by Step

If a = 4.7, b = 2.3, and c = 7.0, then triangle ABC can not exist.
If side c is the longest side, then $a+b \gt c$ in order for the triangle to exist.
If $a+b \leq c$, then we can not join side a and side b such that they reach from one end of side c to the other end of side c. Therefore, a triangle could not be formed.