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JEE Mains · Maths · STD 11 - 4.1 complex nubers

यदि सम्मिश्र संख्या \(z=2-i\left(2 \tan \frac{5 \pi}{8}\right)\) का मापांक \(r\) और कोणांक  \(\theta\) है, तो \((r, \theta)\) क्या हैं?

  1. A  \(\left(2 \sec \frac{3 \pi}{8}, \frac{3 \pi}{8}\right)\)
  2. B \(\left(2 \sec \frac{3 \pi}{8}, \frac{5 \pi}{8}\right)\)
  3. C  \(\left(2 \sec \frac{5 \pi}{8}, \frac{3 \pi}{8}\right)\)
  4. D  \(\left(2 \sec \frac{11 \pi}{8}, \frac{11 \pi}{8}\right)\)
Verified Solution

Answer & Solution

Correct Answer

(A)  \(\left(2 \sec \frac{3 \pi}{8}, \frac{3 \pi}{8}\right)\)

Step-by-step Solution

Detailed explanation

\( z=2-i\left(2 \tan \frac{5 \pi}{8}\right)=x+i y(\text { let }) \) \( r=\sqrt{x^2+y^2} \theta=\tan ^{-1} \frac{y}{x} \) \( r=\sqrt{(2)^2+\left(2 \tan \frac{5 \pi}{8}\right)^2} \) \( =\left|2 \sec \frac{5 \pi}{8}\right|=\left|2 \sec \left(\pi-\frac{3 \pi}{8}\right)\right|\)…
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