Answer
$b = 2\sqrt{3}$
Work Step by Step
The terminal side of $60^{\circ}$ in standard position is represented by the blue line in the figure.
We can find $b$ from the triangle in the figure
$$\tan(60^{\circ}) = \frac{b}{2}$$
$$b = 2\times \tan(60^{\circ})$$
$$\therefore b = 2\sqrt{3}$$
