OCR FP1 AS 2021 June — Question 2

Exam BoardOCR
ModuleFP1 AS (Further Pure 1 AS)
Year2021
SessionJune
TopicComplex Numbers Arithmetic
TypeMulti-part questions with division as one step

2 In this question you must show detailed reasoning.
The complex number \(7 - 4 \mathrm { i }\) is denoted by \(z\).
  1. Giving your answers in the form \(a + b \mathrm { i }\), where \(a\) and \(b\) are rational numbers, find the following.
    1. \(3 z - 4 z ^ { * }\)
    2. \(( z + 1 - 3 \mathrm { i } ) ^ { 2 }\)
    3. \(\frac { z + 1 } { z - 1 }\)
  2. Express \(z\) in modulus-argument form giving the modulus exactly and the argument correct to 3 significant figures.
  3. The complex number \(\omega\) is such that \(z \omega = \sqrt { 585 } ( \cos ( 0.5 ) + \mathrm { i } \sin ( 0.5 ) )\). Find the following.
    • \(| \omega |\)
    • \(\arg ( \omega )\), giving your answer correct to 3 significant figures