$\mathop {\lim }\limits_{x \to 0} \frac{{3\sin x - \sin 3x}}{{{x^3}}} = $

If $\theta$ is a small and positive number,then which of the following is/are correct?

$\lim _{x}$ ${\rightarrow 0} \frac{\tan \left(\left[-\pi^2\right] x^2\right)-x^2 \tan \left(\left[-\pi^2\right]\right)}{\sin ^2 x}$ equals

$\lim _{x \rightarrow 0} \frac{(1-\cos 2 x)}{x \tan 2 x+\frac{2 x}{3} \tan 3 x} = $

$\mathop {\lim }\limits_{\theta \to 0} \frac{{1 - \cos \theta }}{{{\theta ^2}}} = $

$\mathop {\lim }\limits_{x \to 0} \frac{{\sin (\pi {{\cos }^2}x)}}{{{x^2}}} = $