Can someone help me create an equation from sunset data?

I know the local sunset max is 15:08 on June 21 and sunset min 9:13 on Dec. 20.

I can get the Amp from (max-min)/2 = 2.975

B value (max+min)/2 = 12.105

Period, T, = 2(pi)/365 = .0172

Vertical shift wx-@=(pi)/2, so (pi/2)-182(.0172)= -1.56, where 182 represents the time in days between max-min.

I get y=2.975sin(.0172x-1.56)+12.105

This gets me very close, but seems off by a few days. What am I doing wrong?

Perfessor Jack of Clubs

http://mymathforum.com/images/ranks/clover_1.gif **Posts:** 9 **Joined:** Sat Feb 05, 2011 8:34 am