Huon has been learning that square roots of complex numbers are well... complicated.
If a, b are both positive real numbers then we have the fact that ∙∙a∙∙b = ∙∙ab. For a complex number this is no longer true. If w is a complex number with
r = |w| and θ = Arg(w)
then we define the complex squareroot of w to be
∙∙r exp(iθ) = ∙∙r exp(iθ/2).
Note very carefully that θ is the principal argument of w.
(a) Using this definition, enter the following complex squareroots in Cartesian form:
(i) ∙∙-1 =
(ii) ∙∙(-1) × (-1) =
(iii) ∙∙-1 × ∙∙-1 =
Please use Maple syntax for complex number. If your response is -5 + 19i then enter
-5 + 19*I
Note the capital letter I.
(b)
Help Huon understand this definition by using it find the modulus and principal argument of ∙∙z^2 where
z = 25 exp(i 8π/13).
|∙∙z| =
Arg(∙∙z^2) =
(c)
For part (c) we are again using z = 25 exp(i 8π/13). Consider a complex number w of the form
w = ρ exp(iφ)
where ρ is a positive real number and φ ∈ ℝ. What is the largest interval containing zero, so that ∙∙zw = ∙∙z∙∙w. Enter your answer in interval notation.
We need φ ∈
Enter your response in the box above using standard interval notation, for example, (-6,11] . The numbers you enter should use Maple syntax with a * for multiplication, for example, 40*sqrt(Pi) for 40∙∙π and infinity for ∞.
If your answer to part (c) above is incorrect, partial marks may be awarded for any working provided below: