V(X)=asin(bx-c)+d for this problem. tides go up and down over a 14.4 hour period . the average depth of Valencia river is 15.5 ft and ranges from 14 to 17 ft, and the variation in the depth can be approximated by a sine curve. Find an equation to approximately model the variation V if x is the number of hours after midnight and high tide occurs at 8:00 am.