What is the general equation of a cosine function with an amplitude of 3, a period of 4 pi, and a horizontal shift of Negative pi? y = 4 pi cosine (3 (x minus pi)) y = 3 cosine (4 pi (x pi)) y = 3 cosine (0. 5 (x pi)) y = 4 pi cosine (0. 2 (x pi)).