Am pretty confuse in need of Hope

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

The graph is supposed to show f(x) = 3 sin (x/4+1) - 1/2. which of the following are correctly represented in the graph? select two of the following that apply.

What is the value of the discrimination for the quadratic equation 0=×2+2+×2