For this problem, I think there is no need for the details of 12 inches width and 4 inches length. This is because an equation is already given. It was clearly specified that A as a function of θ represents the area of the opening. Then, we are asked to find exactly that: the area of opening. Moreover, the value of θ was also given. Therefore, I am quite sure that the initial details given are for the purpose of red herring only.
So, all we have to do is substitute θ=45° to the function given.
A = 16 sin 45° ⋅ (cos 45° + 1)
The angle 45° is a special angle in trigonometry. So, it would be easy to remember trigonometric functions of this angle. Sine of 45° is equal to √2/2 while cosine of 45° is also √2/2.
A = 16(√2/2) ⋅ (√2/2 + 1)
A = 8+8√2
A = 19.31 square inches
Step-by-step explanation:
We have given that,
The inner radius of a bicycle wheel is 12 inches.
It is required to find the expression to find the inside circumference of this wheel.
The outer surface of the wheel is equal to its circumference. It is given by :

r is radius of wheel

This is the required explanation.
Usually there will be a line through the graph, labeling f(x) = ..... so plug in f(3) and follow the line on the x-axis to look for 3 then find y
Answer:
I believe it should be $9.15
Step-by-step explanation: