If each shelf is to contain exactly 3 new CDs and there are only 5 shelves, only 15 can be placed in the rack. So, the answer to the second question is no. The same goes for the first question as placing 3 or fewer CDs to the shelves will make the rack insufficient for the CDs. 
        
                    
             
        
        
        
Answer:  
=========================================================
Work Shown:
Apply the following trig identity

Now let's rationalize the denominator

----------------------
As confirmation, you can use the idea that if x = y, then x-y = 0. We'll have x = tan(165) and y = -2+sqrt(3). When computing x-y, your calculator should get fairly close to 0, if not get 0 itself. 
Or you can note how

which helps us see that they are the same thing.
Further confirmation comes from WolframAlpha (see attached image). They decided to write the answer as  but it's the same as above.
 but it's the same as above.
 
        
             
        
        
        
Answer:
100/65 because 0.65 is a decimal number
Step-by-step explanation:
hope this helped 
have a great day