trig
posted by rachel .
The function d=8cos2t describes a simple harmonic motion, where d is the distance(in meters) an object travel in t seconds. What is the frequency?

for any y = a cos(kx) or y = a sin(kx)
the period is 2π/k
so for yours the period is 2π/2 = π
So there is one complete "motion" every π seconds