Let the function $f$ be defined by $f(x) = \frac{1}{\sqrt{1-x^2}}.$ Indicate whether the following statements are True (T) or False (F). You must get all answers correct in order to receive credit.
1. 0 is in the domain of $f$
2. All negative real numbers are in the domain of $f$
3. 1 is in the domain of $f$
4. $f(x)$ is never positive.
5. $f(x)$ is never zero.
6. All positive real numbers are in the domain of $f$
7. $f(x)$ is never negative.

Hint: Draw the graph of $f$.