$\frac{d}{dx}(\sin 30^\circ)$ is equal to

Given that $y = \frac{10}{\sin x + \sqrt{3} \cos x}$. The minimum value of $y$ is

The greatest value of the function $-5 \sin \theta + 12 \cos \theta$ is

$\int \frac{3}{(2-x)^2} \, dx$ is equal to $:-$

The value of $\frac{d^2}{dx^2} (4x^3 - 3x^2 + 2x + 1)$ is ..... (in $x - 6$)

Which of the following relation$(s)$ is/are correct?
$(A)\ \sin (90^{\circ}+\theta)=\cos (-\theta)$
$(B)\ \sin (180^{\circ}-\theta)=\cos (90^{\circ}-\theta)$
$(C)\ \sin (360^{\circ}-\theta)=\cos (360^{\circ}-\theta)$
$(D)\ \sin (180^{\circ}+\theta)=\cos (90^{\circ}-\theta)$