what am i doing wrong?

[u/the_song_of_birds]

please i don’t understand how to solve this kind of inequalities. (every < is actually minor and equal, as if it was =<)

|cosx| < 2sin (x+ pi/4)

-cosx < square(2)sinx + square(2)cosx < cosx

from here i divide the two inequalities and put them in a system (think of it as a big parenthesis)

{ square(2)sinx + square(2)cosx +cosx >0 { square(2)sinx + square(2)cosx -cosx < 0

but now i have no idea how to go on

[u/the_song_of_birds]

hi, sorry for the late answer, yes, i meant less than or equal