Problem:
Find the norm and argument (phase angle in radians) of $\frac{6}{5} \left(-\cos \left(\frac{2 \pi }{9}\right)-i \sin \left(\frac{2 \pi }{9}\right)\right)$.
Answer:
Norm: $\frac{6}{5} \sqrt{\sin ^2\left(\frac{2 \pi }{9}\right)+\cos ^2\left(\frac{2 \pi }{9}\right)}$
Argument: $-\frac{7 \pi }{9}$
{'source': 'AMPS', 'file': 'amps/mathematica/algebra/complex_norm_and_arg/24586.txt'}