Thread: graph to solve

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!

Originally Posted by belloway

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!

your equations is a little bit ambiguous is this what you mean:



if you are solving for t then rewrite the equation to t= and plug in 20
for D

Originally Posted by belloway

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!

This problem tells you exactly what to do! Have you done that? Have you put this function, into a "graphing utility" (such as a graphing calculator), as well as the function y= 20, to see where the first is above the second graph? The whole point of suggesting you use a "graphing utility" is that they do not expect you to solve that equation.

screenshots ...

Thank You so much for all your help! I really appreciate it!

Okay, what answer did you come up with?

Days 133 to 233. I know it's right because it was in the back of my book. I hasd the answer just didn't know how to get to it. Thanks again.

Days 133 to 233. I know it's right because it was in the back of my book. I hasd the answer just didn't know how to get to it. Thanks again.