Answer:
2
Explanation:
The basic 30-60-90 triangle ratio is:
Side opposite the 30° angle: x
Side opposite the 60° angle: x√3
Side opposite the 90° angle: 2x
Here, the side opposite the 90° angle is 4.
This means that 2x = 4 and, thus, x = 2.
Since b is the side opposite the 30° angle, b = x, so it is 2.