Here is the equation:

You need to find f(3). To do that, substitute all the x's with 3:

The first thing you need to do is multiply 4 by 3. Multiply:

Here is your new equation:

To get your answer, you need to add 12 and 1. Add:

That means:

<em>If you have any questions, feel free to ask in the comments! :)</em>
The domain is all real numbers. (-infinity, infinity)
You can put any real number x value into the function.
Answer:
34.78 feet
Step-by-step explanation:
1) using the cosine function, I did cos(43)=x/51
This is because cosine is equal to adjacent over hypotnuse
Once I found x, I used the pythagorean theorem to get 34.78 feet
91$ per day you divid 455$ by the 5 days and get 91$