Write the given expression in algebraic form
err algebraic form?
let $\displaystyle \theta = \arcsin\left(\frac{x}{2}\right)$
then $\displaystyle \sin{\theta} = \frac{x}{2} = \frac{opposite}{hypotenuse}$
using Pythagoras ...
$\displaystyle adjacent = \sqrt{4 - x^2}$
so ...
$\displaystyle \cot\left[\arcsin\left(\frac{x}{2}\right)\right] = \cot{\theta} = \frac{adjacent}{opposite} = \frac{\sqrt{4-x^2}}{x}$