If an object is traveling in the y-direction with acceleration ay = 20cos(3pi * t) (in radians), what would be the object's position in the y-direction after 11 seconds, with these initial conditions?

vy0 = 12 m/s, initial position = 3 meters

I think the answer is 135 meters.

I think you forgot that cos(33pi) = -1, not zero.