The water level varies from 12 inches at low tide to 52 inches at high tide.Low tide occurs at 9:15 AM and high tide occurs at 3:30 PM. What is a cosine function that models the variation in inches above and below the water level as a function of time in hours since 9:15AM?

My answer is = 20 cos (x-3.5)+32 could someone tell me if this is correct

Question

The water level varies from 12 inches at low tide to 52 inches at high tide.Low tide occurs at 9:15 AM and high tide occurs at 3:30 PM. What is a cosine function that models the variation in inches above and below the water level as a function of time in hours since 9:15AM?

My answer is = 20 cos (x-3.5)+32  could someone tell me if this is correct

anonymous · Answer

@Hero

anonymous · Answer

your function should be negative, since the low tide occurs first

anonymous · Answer

and why do you subtract x by 3.5? O.o

anonymous · Answer

the function is at minimum when t=0, and that fits with the description 9:15 AM. So I don't think that the 3.5 is necessary

anonymous · Answer

hah I'm not sure thats why I'm asking for help, do you know what it could be? @alias

anonymous · Answer

other than that, I think everything is correct

anonymous · Answer

so what would the answer be -20 cos (0)+32? @alias

anonymous · Answer

-20 cos(x) + 32

anonymous · Answer

okay thanks a lot for the help!

anonymous · Answer

yw :)