MCQ
For any integer $k$ , let $w_k$ = $\cos \left( {\frac{{k\pi }}{{11}}} \right) + i\,\sin \left( { \frac{{k\pi }}{{11}}} \right)$ where $i$ = $\sqrt {-1}$ . The value of the expression $\frac{{\sum\limits_{k = 1}^8 {\left| {{w_{2k + 1}} - {w_{2k}}} \right|} }}{{\sum\limits_{k = 1}^4 {\left| {{w_{3k - 1}} - {w_{3k - 2}}} \right|} }}$ is
  • A
    $1$
  • $2$
  • C
    $3$
  • D
    $4$

Answer

Correct option: B.
$2$
b
$\frac{\left|w_{3}-w_{2}\right|+\left|w_{5}-w_{4}\right|+\left|w_{7}-w_{6}\right|+\ldots .+\left|w_{17}-w_{16}\right|}{\left|w_{2}-w_{1}\right|+\left|w_{5}-w_{9}\right|+\left|w_{8}-w_{7}\right|+\left|w_{11}-w_{10}\right|}$

$\therefore \quad\left|\mathrm{w}_{1}-\mathrm{w}_{2}\right|=\left|\mathrm{w}_{2}-\mathrm{w}_{3}\right|=\ldots \ldots=\mathrm{a}$

$\therefore \quad$ Ratio $=\frac{8 \mathrm{a}}{4 \mathrm{a}}=2$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free