Math Video Library Collection

Call the horizontal axis the real axis and the vertical axis the imaginary axis. Now complex numbers can be graphed in this complex plane. The sum of two complex numbers can be represented graphically by the vector that is the resultant of the sum of vectors corresponding to the two numbers. Trigonometric or Polar Form of a Complex Number The expression r(cos  + i sin  ) Notation: cos  + i sin  is sometimes written cis  . Using this notation, r(cos  + i sin  ) is written r cis . The number r is called the modulus or absolute value of the complex number x + yi. Angle  is called the argument of the complex number x + yi.