Final answer:
In a simple harmonic motion equation, the frequency can be calculated as 1 divided by the period.
Step-by-step explanation:
In a simple harmonic motion equation of the form d = A cos(ωt), where ω is the angular frequency, the frequency f is defined as f = 1/T, where T is the period.
In this case, we have d = 0 cos(π/2t). Since the coefficient of t is π/2, the angular frequency ω is π/2.
Therefore, the period T = 2π/ω is 2π/(π/2) = 4, and the frequency f = 1/T = 1/4 = 0.25.