Change the cos function into a sin function
d(t)= -8cos (pi(t)/30)+8
cos(x) = sin(pi/2 - x)
That's what the co- in cosine means: sine of the co-mplementary angle.
d(t)= -8cos (pi(t)/30)+8
That's what the co- in cosine means: sine of the co-mplementary angle.