Modulus and argument with operations

Questions that require finding modulus and/or argument after performing complex number operations (multiplication, division, addition) or for expressions involving multiple complex numbers.

1 questions

OCR MEI FP1 2012 June Q2
2 You are given that \(z _ { 1 }\) and \(z _ { 2 }\) are complex numbers.
\(z _ { 1 } = 3 + 3 \sqrt { 3 } \mathrm { j }\), and \(z _ { 2 }\) has modulus 5 and argument \(\frac { \pi } { 3 }\).
  1. Find the modulus and argument of \(z _ { 1 }\), giving your answers exactly.
  2. Express \(z _ { 2 }\) in the form \(a + b \mathrm { j }\), where \(a\) and \(b\) are to be given exactly.
  3. Explain why, when plotted on an Argand diagram, \(z _ { 1 } , z _ { 2 }\) and the origin lie on a straight line.