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4-1.Complex numbers
normal
સંકર સંખ્યા $\sin \,\frac{{6\pi }}{5}\, + \,i\,\left( {1\, + \,\cos \,\frac{{6\pi }}{5}} \right)$ નો કોણાક મેળવો
A
$\frac{{6\pi }}{5}$
B
$\frac{{5\pi }}{6}$
C
$\frac{{9\pi }}{10}$
D
$\frac{{2\pi }}{5}$
Solution
$\sin \frac{6 \pi}{5}+i\left(1+\cos \frac{6 \pi}{5}\right)$
lies in ${2^{nd}}$ quadrant and
$\left|\frac{1+\cos \frac{6 \pi}{5}}{\sin \frac{6 \pi}{5}}\right|=\left|\cot \left(\frac{3 \pi}{5}\right)\right|=\left|\cot \left(\frac{\pi}{2}+\frac{\pi}{10}\right)\right|=\tan \frac{\pi}{10}$
${2^{nd}}$ quadrant $\Rightarrow \pi-\frac{\pi}{10}$
Standard 11
Mathematics