যদি,$0^{\circ}<\theta<180^{\circ}$ হয় তবে $\sqrt{2+\sqrt{2+\sqrt{\ldots \ldots \ldots+2(1+\cos \theta)}}}=?(n$ সংখক 2)

$2 \cos \frac{\theta}{2^{n-1}}$

$2 \cos \frac{\theta}{2^{n}}$

$2 \cos \frac{\theta}{2^{n+1}}$

$2 \cos \frac{n \theta}{2}$

$2 \cos \frac{\theta}{2 n}$