If f(x) = 1/12x+4 and f(a)= 8, what is the value of a

Which sum or difference identity would you use to verify that cos (180° - q) = -cos q? a.) sin (a -b) = sin a cos b – cos a sin b b.) cos (a -b) = cos a cos b – sin a sin b c.) cos (a -b) = cos a cosb + sin a sin b d.) sin (a + b) = sin a cos b + cos a sin b

Will give a: 122 b: 90 c: 48 d: 180

Arock was dropped from the top of a building. the function that describes the height after it was dropped is f(x)=64-16x^2. what are the zeros of the function and what do they mean?