Which of the following would best represent a cosine function with an amplitude of 3, a period of pi over 2, and a midline at y = −4? f(x) = −4 cos 4x + 3 f(x) = 3 cos(x − pi over 2) − 4 f(x) = 4 cos(x − pi over 2) + 3 f(x) = 3 cos 4x − 4