Quote:
Originally Posted by keenan87
In Saskatchewan, the sun rises at 09:17 on December 21 and at 04:35 on June 22. Because there is no daylight savings time in Saskatchewan, the time the sun rises on any other day can be predicted from a sinusodial graph with a period of 365 days.
Write a sinusoidal equation that realtes the time the Sun rises to the day of the year.
I got
y=2.35cos(2pi/365)(x-173)+6.933
is this the right way?
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From an extremely quick glance, while it seems you're definetly on the right track, from the wording of the question it would seem that the variable, x, should be the day of the year and not some arbitrary value.
So on Jan 1, x should equal 1. Likewise on June 22, x should be 173 and 355 for when it's Dec 21. A simple shift of you're equation would fix this.
y=2.35cos((2pi/365)(x+10))+6.933
gives the value of y for Dec 21 (x=355) of 9.283 (9:17)
and the value of y for June 22 (x=173) of 4.5831 (4:35)
Although I'm tired, so quite possibly I screwed up on something and you're original answer is right.