4. (a) Express the complex number \(18 \sqrt { 3 } - 18 \mathrm { i }\) in the form
$$r ( \cos \theta + \mathrm { i } \sin \theta ) \quad - \pi < \theta \leqslant \pi$$
(b) Solve the equation
$$z ^ { 4 } = 18 \sqrt { 3 } - 18 i$$
giving your answers in the form \(r \mathrm { e } ^ { \mathrm { i } \theta }\) where \(- \pi < \theta \leqslant \pi\)
| VIXV SIHIANI III IM IONOO | VIAV SIHI NI JYHAM ION OO | VI4V SIHI NI JLIYM ION OO |