Answer:
the desired range is 0° < angle < 180°
Step-by-step explanation:
If 2x were just slightly less than b, then the angle opposite the base would be just less than 180 degrees.
The larger the value of x, the further the intersection of the two congruent sides is moved away from the base b. The angle between these two congruent sides would approach but never equal zero.
Thus, the desired range is 0° < angle < 180°
