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COMEDK2017MathematicsComplex Number

If z=r e^ i , then |e^ i z |=

Options

  1. A1
  2. Be^ 2 r
  3. Ce^ r
  4. De^ -r

Correct answer

D. e^ -r

Step-by-step solution

We have, aligned z &=r e^ i =r( +i ) i z &=i r( +i ) &=i r +i² r =-r +i r |e^ i z | &= |e^ (-r +i r ) | &= |e^ -r | |i r | &=e^ -r [ ²(r )+ ²(r ) ] &=e^ -r 1=e^ -r aligned

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