How would I find the smallest positive integer N such that $ (w)^N $ is a real number?
Given that
$$w = 8e^{\dfrac{i7\pi}{6}}.$$
Asked
Active
Viewed 1,795 times
0
-
1Hint. Start computing some powers and remember the value of $e^{i\pi}$ – Ethan Bolker Nov 18 '17 at 18:19
1 Answers
1
So $w = 8e^{i7 {\pi} /6}$. Use an identity which says $e^{i {\theta}} = cos {\theta} + isin {\theta}$. So sin and cos are real valued for reals. So we have to make $sin{N7 {\pi}/6} = 0$. Since $sin {n {\pi}} = 0$ for all n in integers. So make $N7 {\pi}/6$ into an integer and $N \geq 1$ will give $N = 6$.
Shri
- 774
-
https://math.stackexchange.com/questions/3510/how-to-prove-eulers-formula-eit-cos-t-i-sin-t – lab bhattacharjee Nov 18 '17 at 18:36