If $x+(1 / x)=2 \cos \theta$, then the value of $x$ is

$\cos 2 \theta+i \sin 2 \theta$

$(\cos \theta+i \sin \theta)^2$

$\cos 4 \theta-i \sin 4 \theta$

JEE MATHEMATICS MCQ: COMPLEX NUMBERS

1 Easy

1 of 1

Application +4 | -1

x+(1 / x)=2 \cos \theta

, then the value of

x

View answer and explanation

Correct option: A

\cos \theta \pm i \sin \theta

Option A (

\cos \theta \pm i \sin \theta

) is the correct solution because it is derived by solving the quadratic equation resulting from the given equation.

Practice All Chapter MCQs →

{\left| {1 - i} \right|^x} = {2^x}

|z|=1

z \neq \pm 1

z, \frac{z}{1-z^2}

\left|z_r-r\right| \leq r, \forall r=1,2,3, \ldots, n

\left|\sum\limits_{r=1}^n z_r\right|

(z+a b)^3=a^3

a \neq 0

\alpha, \beta

\gamma

|\alpha-\beta|

{z^2} + {\left| z \right|^2} = 0,

z \in C

2x = - 1 + \sqrt 3 i

{\left( {1 - {x^2} + x} \right)^6} - {\left( {1 - x + {x^2}} \right)^6}