$\frac{d}{d x}\left(\cos 7 x^{\circ}\right)=$ কত ?

$\sin 7 x^{\circ}$

$-7 \sin 7 x^{\circ}$

$-\frac{7 \pi}{180} \sin 7 \mathrm{x}^{\circ}$

$\frac{7 \pi}{180} \sin 7 x^{\circ}$