When \(a \ne 0\), there are two solutions \(ax^2 + bx + c = 0\)

$\pi =a\xb7\left({2}^{n+1}\right){\left\{2\u2013\sqrt{2+\sqrt{2+\sqrt{2+\dots {n}^{thterm}+\sqrt{a}}}}\right\}}^{{\displaystyle \frac{1}{2}}}$*\( \lim_{x \rightarrow 0} \frac{Sin x}{x} = 1\) [where x is measured in radian]*