# Find $\sqrt{- \frac{5228171817}{100000000} - i}$

This calculator will find all $n$-th roots ($n = 2$) of the complex number $- \frac{5228171817}{100000000} - i$, with steps shown.

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Find $\sqrt{- \frac{5228171817}{100000000} - i}$.

### Solution

The polar form of $- \frac{5228171817}{100000000} - i$ is $\frac{\sqrt{27343780548073081489}}{100000000} \left(\cos{\left(- \pi + \operatorname{atan}{\left(\frac{100000000}{5228171817} \right)} \right)} + i \sin{\left(- \pi + \operatorname{atan}{\left(\frac{100000000}{5228171817} \right)} \right)}\right)$ (for steps, see polar form calculator).

According to the De Moivre's Formula, all $n$-th roots of a complex number $r \left(\cos{\left(\theta \right)} + i \sin{\left(\theta \right)}\right)$ are given by $r^{\frac{1}{n}} \left(\cos{\left(\frac{\theta + 2 \pi k}{n} \right)} + i \sin{\left(\frac{\theta + 2 \pi k}{n} \right)}\right)$, $k=\overline{0..n-1}$.

We have that $r = \frac{\sqrt{27343780548073081489}}{100000000}$, $\theta = - \pi + \operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}$, and $n = 2$.

• $k = 0$: $\sqrt{\frac{\sqrt{27343780548073081489}}{100000000}} \left(\cos{\left(\frac{\left(- \pi + \operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}\right) + 2\cdot \pi\cdot 0}{2} \right)} + i \sin{\left(\frac{\left(- \pi + \operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}\right) + 2\cdot \pi\cdot 0}{2} \right)}\right) = \frac{\sqrt[4]{27343780548073081489}}{10000} \left(\cos{\left(- \frac{\pi}{2} + \frac{\operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}}{2} \right)} + i \sin{\left(- \frac{\pi}{2} + \frac{\operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}}{2} \right)}\right) = \frac{\sqrt[4]{27343780548073081489} \sin{\left(\frac{\operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}}{2} \right)}}{10000} - \frac{\sqrt[4]{27343780548073081489} i \cos{\left(\frac{\operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}}{2} \right)}}{10000}$
• $k = 1$: $\sqrt{\frac{\sqrt{27343780548073081489}}{100000000}} \left(\cos{\left(\frac{\left(- \pi + \operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}\right) + 2\cdot \pi\cdot 1}{2} \right)} + i \sin{\left(\frac{\left(- \pi + \operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}\right) + 2\cdot \pi\cdot 1}{2} \right)}\right) = \frac{\sqrt[4]{27343780548073081489}}{10000} \left(\cos{\left(\frac{\operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}}{2} + \frac{\pi}{2} \right)} + i \sin{\left(\frac{\operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}}{2} + \frac{\pi}{2} \right)}\right) = - \frac{\sqrt[4]{27343780548073081489} \sin{\left(\frac{\operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}}{2} \right)}}{10000} + \frac{\sqrt[4]{27343780548073081489} i \cos{\left(\frac{\operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}}{2} \right)}}{10000}$

$\sqrt{- \frac{5228171817}{100000000} - i} = \frac{\sqrt[4]{27343780548073081489} \sin{\left(\frac{\operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}}{2} \right)}}{10000} - \frac{\sqrt[4]{27343780548073081489} i \cos{\left(\frac{\operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}}{2} \right)}}{10000}\approx 0.069147298993848 - 7.230940431158187 i$A
$\sqrt{- \frac{5228171817}{100000000} - i} = - \frac{\sqrt[4]{27343780548073081489} \sin{\left(\frac{\operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}}{2} \right)}}{10000} + \frac{\sqrt[4]{27343780548073081489} i \cos{\left(\frac{\operatorname{atan}{\left(\frac{100000000}{5228171817} \right)}}{2} \right)}}{10000}\approx -0.069147298993848 + 7.230940431158187 i$A