The function $f(x) = \sin x - \cos x$ is ........

If $f(x) = \log \left( \frac{1 + x}{1 - x} \right)$,then $f(x)$ is

Let $f$ be an odd function defined on the set of real numbers such that for $x \geq 0$,$f(x) = 3 \sin x + 4 \cos x$. Then $f(x)$ at $x = -\frac{11\pi}{6}$ is equal to:

Which of the following is an even function?

The equation $6^{x}+8^{x}=10^{x}$ has

Statement $-1$: Any function $f(x)$ is an even function if $f(-x) = f(x)$ for all $x$ in its domain.
Statement $-2$: The function $f(x) = \frac{1}{\sqrt{1 - x^2}} + \left[ \frac{x^2 + x + 1}{4} \right]$,where $[.]$ denotes the greatest integer function,is an even function.