How to get correct answer

[mimie]

I only manage to get one of the answer correct which is 32°30' but unable to get 191°6' as another answer. Can someone teach me how to get 191°6'? Thanks.

 

[Harry_the_cat]

Don't reject your second answer of theta/2 = -84^o 27'.
This leads to theta = -168^o54'.
Now this is outside the domain given, but what is an angle coterminal with this one which IS in the domain? (hint: add 360^o)

 

[mimie]

I don't understand why cannot reject -84°27', can you explain it in simple words?

 

[Harry_the_cat]

Because at that stage you haven't yet found theta. When you get theta = -168^o54', you 'reject' that answer but find an angle in your domain that is coterminal with it ie -168^o54' + 360^o.