$$$\sqrt[3]{i}$$$을(를) 구하시오
사용자 입력
$$$\sqrt[3]{i}$$$을(를) 구하시오.
풀이
$$$i$$$의 극형식은 $$$\cos{\left(\frac{\pi}{2} \right)} + i \sin{\left(\frac{\pi}{2} \right)}$$$입니다(풀이 단계는 극형식 계산기를 참조하세요).
드무아브르의 공식에 따르면, 복소수 $$$r \left(\cos{\left(\theta \right)} + i \sin{\left(\theta \right)}\right)$$$의 모든 $$$n$$$제곱근은 $$$r^{\frac{1}{n}} \left(\cos{\left(\frac{\theta + 2 \pi k}{n} \right)} + i \sin{\left(\frac{\theta + 2 \pi k}{n} \right)}\right)$$$, $$$k=\overline{0..n-1}$$$로 주어진다.
다음이 성립한다: $$$r = 1$$$, $$$\theta = \frac{\pi}{2}$$$, 및 $$$n = 3$$$.
- $$$k = 0$$$: $$$\sqrt[3]{1} \left(\cos{\left(\frac{\frac{\pi}{2} + 2\cdot \pi\cdot 0}{3} \right)} + i \sin{\left(\frac{\frac{\pi}{2} + 2\cdot \pi\cdot 0}{3} \right)}\right) = \cos{\left(\frac{\pi}{6} \right)} + i \sin{\left(\frac{\pi}{6} \right)} = \frac{\sqrt{3}}{2} + \frac{i}{2}$$$
- $$$k = 1$$$: $$$\sqrt[3]{1} \left(\cos{\left(\frac{\frac{\pi}{2} + 2\cdot \pi\cdot 1}{3} \right)} + i \sin{\left(\frac{\frac{\pi}{2} + 2\cdot \pi\cdot 1}{3} \right)}\right) = \cos{\left(\frac{5 \pi}{6} \right)} + i \sin{\left(\frac{5 \pi}{6} \right)} = - \frac{\sqrt{3}}{2} + \frac{i}{2}$$$
- $$$k = 2$$$: $$$\sqrt[3]{1} \left(\cos{\left(\frac{\frac{\pi}{2} + 2\cdot \pi\cdot 2}{3} \right)} + i \sin{\left(\frac{\frac{\pi}{2} + 2\cdot \pi\cdot 2}{3} \right)}\right) = \cos{\left(\frac{3 \pi}{2} \right)} + i \sin{\left(\frac{3 \pi}{2} \right)} = - i$$$
정답
$$$\sqrt[3]{i} = \frac{\sqrt{3}}{2} + \frac{i}{2}\approx 0.866025403784439 + 0.5 i$$$A
$$$\sqrt[3]{i} = - \frac{\sqrt{3}}{2} + \frac{i}{2}\approx -0.866025403784439 + 0.5 i$$$A
$$$\sqrt[3]{i} = - i$$$A
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