Answer:
Identity (a) can be re-written as

which we already proven in another question, while for idenity (b)

step A is simply expressing each function in terms of sine and cosine.
step B is adding the terms on the LHS while multiplying the one on RHS.
step C is replacing the term on the numerator with the equivalent from the pithagorean identity 
Answer:
The zeroes are 3 and -2...if u need explanation I am open but seem in a hurry
Circunference=2 times pi time r
if pi=3 and r=4.5
circunerence=2 times 3 times 4.5=3 times 2 tiimes 4.5=3 times 9=27
answer is 27cm
Center c and a scale factor of 2