# Question #8bcb5

Well, I think you are right; if you have $\sqrt{225 - {x}^{2}}$ the allowed values for $x$ are those for which the argument of the square root is $\ge 0$, i.e.:
$225 - {x}^{2} \ge 0$ so that:
$x \le \pm 15$
This represents the interval in between the values of $- 15$ and $+ 15$:
You can check using a value in the middle of the interval such as $x = 0$ which gives you:
$\sqrt{225} = 15$ that is ok.