I just need some kind of explanation in layman's terms of what exactly is going on here. It seems as though I am missing some key element from trig. I am in a Signals class and the book lacks an explanation of the reduction used and ultimately why.
I have attached a .pdf of the files.
View attachment Document1.pdf
The Attempt at a Solution
Ok, so in "b": I do not understand the simplification or reduction to the side, where 4pi is added. Also I think the same method occurs in the third answer of "d".
Also, is the reason there are 3 answers for "d" because of the cube root? If someone could just provide a short explanation as to why, that would be helpful.
Thank you so much in advance!