Mathematics

Mathematics

Problem

Let rr and θ\theta respectively be the modulus and amplitude of the complex number z=2−i(2tan⁡5π8)z = 2 - i \left( 2 \tan \frac{5\pi}{8} \right), then (r,θ)(r, \theta) is equal to [Jan. 29, 2024 (II)] (a) (2sec⁡11π8,11π8)\left( 2 \sec \frac{11\pi}{8}, \frac{11\pi}{8} \right) (b) (2sec⁡5π8,3π8)\left( 2 \sec \frac{5\pi}{8}, \frac{3\pi}{8} \right) (c) (2sec⁡3π8,5π8)\left( 2 \sec \frac{3\pi}{8}, \frac{5\pi}{8} \right) (d) (2sec⁡3π8,3π8)\left( 2 \sec \frac{3\pi}{8}, \frac{3\pi}{8} \right)

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