#sin vs cos in this question?

15 messages · Page 1 of 1 (latest)

hollow bramble
#

My answer is the red, supposedly the correct answer is in the green.
If we take 10 am as between midnight and 10 pm, then wouldn’t it be modeled as a function using cos?
My approach was to take the 10am as the first point, since it’s 18 degrees, that’d be the maximum point, and then I’d just shift it to the right by 10 hours to account for starting at midnight

I’ve also attached my attempt ( the graph doesn’t visualize accounting for the 10 hour phase shift, it’s added in the calculation part below

Wouldn’t using the sin function assume that, it’s exactly 10.5 degrees during midnight? (Which I don’t think is given)

If I’m wrong, please try to explain the logic of why sin is used, and if the supposedly correct answer is wrong, please let me know. THANKS

IMG_1422.png IMG_1423.jpg
paper valveBOT
hollow bramble
#

It sorta does account for the 10 hour shift in my graph, i just indicated that by the 10,18 on the top

wintry ferry
#

First off, you could have found an equivalent solution using cos, since they're just translations of one another, although the "quick" way to do this is to use sin because you're given the points at the halfway point.

You say that Wouldn’t using the sin function assume that, it’s exactly 10.5 degrees during midnight? (Which I don’t think is given), but if in the green one you plug in t=10, the temperature is 10.5, which is the "halfway" temperature they've given.

#

WIth your cos equation, you would the highs and lows at 10AM and 10PM

hollow bramble
#

This is totally an understanding error then, I thought the temperature peaks at 10 am, and then reaches its lowest at 10 am

#

Right, this makes much more sense thank you

hollow bramble
wintry ferry
#

You could've worked with the peaks to use cos by noticing that the information given means that the peaks are attained at 4am and 4pm

#

But then it's a bit more work for not much

#

So yes in general if you're given the averages, use sin, if you're given the peaks, use cos

hollow bramble
#

THANKS, will do

#

Closing the post now

#

.close