Question 1413b

Complex Numbers
2013 Paper 1 Question 8 Variant

Question

The complex number z{z} is given by z=eiθ,{z=\mathrm{e}^{\mathrm{i}\theta},} where r>0{r>0} and π<θπ{-\pi< \theta \leq \pi}.
(a)
Given that w=(1+3i)z,{w=(- 1 + \sqrt{3} \mathrm{i})z, } find w{\left|w\right|} in terms of r{r} and argw{\arg w} in terms of θ.{\theta.}
[2]
(b)
Given that arg(z6w2)=π,{\displaystyle \arg \left( \frac{z^{6}}{w^2} \right) = -\pi,} find θ.{\theta.}
[3]

Answer