Let r and respectively be the modulus and amplitude of the complex number z=2-i (2 5 8 ), then (r, ) is equal to
- (2 11 8, 11 8 )
- (2 3 8, 3 8 )
- (2 5 8, 3 8 )
- (2 3 8, 5 8 )
Answer
(2) (2 3 8, 3 8 )
Solution
5 8=- 3 8 z=2+i (2 3 8 )
=2 3 8 ( 3 8+i 3 8 )
3 8>0 and 3 8 (- , ]
r=2 3 8, = 3 8
Answer: (2)