Answer:
A. y = 3 cos (1/2) x.
Step-by-step explanation:
The y-intercept is 3 so it will contain 3 cos x (because y = cos x passes through (0, 1).
The graph of 3 cos x has been stretched horizontally by a factor 2 ( 3 cos x would pass through (π/2, 0) whereas the given graph passes through (π, 0).
So the equation is 3 cos(1/2) x
