Question

The function f(t) = 3 cos(pi over 6t) + 5 represents the tide in Blastic Sea. It has a maximum of 8 feet when time (t) is 0 and a minimum of 2 feet. The sea repeats this cycle every 12 hours. After nine hours, how high is the tide?

Answer 1

calculate for t = 9 hours
f(9) = 5 ft

Answer 2

Answer: 5 ft

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Explanation:

Replace t with 9 and then use a calculator to compute

f(t) = 3*cos((pi/6)*t) + 5
f(9) = 3*cos((pi/6)*9) + 5
f(9) = 3*cos(9pi/6) + 5
f(9) = 3*cos(3pi/2) + 5
f(9) = 3*0 + 5 <<-- see note below
f(9) = 0 + 5
f(9) = 5

The tide is 5 ft high after nine hours

Note: use a calculator for that step. Make sure to be in radian mode (and not degree mode)