Question

Help please..
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?

12 feet

5 feet

4.5 feet

2.5 feet

Answer 1

@zepdrix

Answer 2

@jim_thompson5910

Answer 3

So they just want us to evaluate this function at t=9 hours.\[\Large\rm f(\color{orangered}{t})=3\cos\left(\frac{\pi}{6}\color{orangered}{t}\right)+5\]\[\Large\rm f(\color{orangered}{9})=3\cos\left(\frac{\pi}{6}\color{orangered}{9}\right)+5\]

Answer 4

Looks like the inside simplifies a lil bit,\[\Large\rm f(9)=3\cos\left(\frac{9\pi}{6}\right)+5\]\[\Large\rm f(9)=3\cos\left(\frac{3\pi}{2}\right)+5\]Do you remember your unit circle? :O
cos(3pi/2) = ?

Answer 5

I do not.. I can put it into Mathway if you like :oo

Answer 6

You... -_-
Yah do that then :p throw it into a calculator, you should get a nice simple answer.

Answer 7

0 correct?

Answer 8

yes. good.

Answer 9

Whoop ^.^

Answer 10

\[\Large\rm f(9)=3\cdot0+5\]

Answer 11

so f(9)=5

Answer 12

yay good job \c:/

Answer 13

And that's my answer ^.^ Thank you!!