cheyenne, wyoming has a latitude of 41 degrees north. At this latitude, the position of the sun at sunrise can be modeled by D=31sin((2pie/365)t-1.4) where t is the time K(in days) and t=1 represents january 1. In this model, D represents the number of degrees north or south of due east that the sun rises. Use a graphing utility to determine the days on which the sun is more than 20 degrees north of due east at sunrise.
can't figure this one
thanks for the help!