Cos x tan x - cos x = 0
Answers:
0 + n pi, pi/4 + 2n pi
0 + n pi, 5pi/4 + 2n pi
Pi/2 + n pi, 5pi/4 + 2n pi
Pi/2 + n pi, pi/4 + 2n pi
                                             
                                          
                                          
                                       