NTA Abhyas JEE Main2020MathematicsComplex NumberPractice
If the complex numbers sin x + i cos 2 x and cos x - i sin 2 x are conjugate of each other, then the number of values of x in the interval 0,2 π is equal to (where, i 2 = - 1 )
Options
- A0
- B1
- C2
- D3
Correct answer
A. 0
Step-by-step solution
sin x = cos x and cos 2 x = sin 2 x ⇒ sin x = cos x & 2 c o s 2 x - 1 = 2 sin x cos x ⇒ sin x = cos x & 2 c o s 2 x - 1 = 2 c o s 2 x ⇒ sin x = cos x & - 1 = 0 (Which is impossible) Hence, no value of x exists