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The imaginary part of \(\frac{1 - i\sqrt{3}}{1 + i\sqrt{3}}\) is

  • A.\(\frac{-1}{2}\)
  • B.\(\frac{1}{2}\)
  • C.\(\frac{\sqrt{3}}{2}\)
  • D.\(\frac{-\sqrt{3}}{2}\)
  • E.\(\frac{\sqrt{3}}{4}\)

Answer: D

The imaginary part is \(\frac{-\sqrt{3}}{2}\).

Multiply numerator and denominator by the conjugate of the denominator, \(1 - i\sqrt{3}\):

\[ \begin{aligned} \frac{(1 - i\sqrt{3})^{2}}{1 + 3} &= \frac{1 - 2i\sqrt{3} - 3}{4} \\ &= \frac{-2 - 2i\sqrt{3}}{4} \\ &= -\frac{1}{2} - \frac{\sqrt{3}}{2}i \end{aligned} \]

The imaginary part is the coefficient of \(i\), \(-\frac{\sqrt{3}}{2}\). \(-\frac{1}{2}\) is the real part, and \(\frac{\sqrt{3}}{2}\) has the wrong sign.

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