If $n$ is an integer and $Z=\cos \theta+i \sin \theta, \theta \neq(2 n+1) \frac{\pi}{2}$, then $\frac{1+Z^{2…
- $i \tan n \theta$
- $i \cot n \theta$
- $-i \tan n \theta$
- $-i \cot n \theta$
Solution
$\begin{aligned} & \frac{1+Z^{2 n}}{1-Z^{2 n}}=\frac{1+(\cos \theta+i \sin \theta)^{2 n}}{1-(\cos \theta+i \sin \theta)^{2 n}}=\frac{1+\cos 2 n \theta+i \sin 2 n \theta}{1-\cos 2 n \theta-i \sin 2 n \theta} \\ & =\frac{\cos n \theta}{i \sin n \theta}\left(\frac{\cos n \theta+i \sin n \theta}{-\cos n \theta-i \sin n \theta}\right)=i \cot n \theta\end{aligned}$
Asked in: AP EAMCET 2024 (21 May Shift 2)