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Highly selective Backlog Qs for JEE MainMathematicsComplex Number

The expression 1 + i tan α 1 - i tan α n - 1 + i tan n α 1 - i tan n α when simplified reduces to

Options

  1. Azero
  2. B2 sin n α
  3. C2 cos n α
  4. Dnone

Correct answer

A. zero

Step-by-step solution

Let 1 + i tan α 1 - i tan α n - 1 + i tan n α 1 - i tan n α = z We know that tan α = sin α cos α ⇒ z = cos α + i sin α cos α - i sin α n - cos n α + i sin n α cos n α - i sin n α From Euler formula, we get ⇒ z = e i α e - i α n - e i n α e - i n α ⇒ z = e 2 i α n - e 2 i n α = e 2 i n α - e 2 i n α = 0 ∴ 1 + i tan α 1 - i tan α n - 1 + i tan n α 1 - i tan n α

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