Question

The phase angle of the system G(s) =s+5/s^2+4s+9;varies between

(a) 0° and 90°

(b) 0° and -90°

(c) 0° and -180°

(d) -90° and -180°

The question was asked in unit test.

My question is based upon Correlation between Time and Frequency Response in chapter Frequency Response Analysis of Control Systems

Answer 1

Correct option is (b) 0° and -90°

For explanation I would say: Phase = tan^−1−11w−w^3/45−^2.