Chapter 2: Problem 144
If \(z=\left[(1+7 i) /(2-i)^{2}\right]\) then the polar form of \(z\) is (a) \(\sqrt{2}[\cos (3 \pi / 4)+\mathrm{i} \sin (3 \pi / 4)]\) (b) \(\sqrt{2}[\cos (\pi / 4)+\mathrm{i} \sin (\pi / 4)]\) (c) \(\sqrt{2}[\cos (7 \pi / 4)+\mathrm{i} \sin (7 \pi / 4)]\) (d) \(\sqrt{2}[\cos (5 \pi / 4)+\mathrm{i} \sin (5 \pi / 4)]\)