Estimate the width of the pie box.

What is the name used to describe a graph where for some value of x, there exists 2 or more different values of y?

With alll of except for the 2 that i did already

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