Question 720944
<pre>
3, x+3, and 9

The three inequalities every triangle must have are

1. first side + second side > third side
2. first side + third side > second side
3. second side + third side > first side

So

1.   3 + x+3 > 9
         6+x > 9
           x > 3

2.   2 + 9 > x+3
        11 > x+3
         8 > x

3.   x+3 + 9 > 3
      x + 12 > 3
           x > -9

All those will be true if 3 < x < 8

Edwin</pre>