College

The circumference of the hub cap of a tire is 81.58 centimeters. Find the area of this hub cap. Use 3.14 for [tex]\(\pi\)[/tex].

If the circumference of the hub cap were smaller, explain how this would change the area of the hub cap.

(Round the final answer to the nearest whole number as needed. Round all intermediate values to the nearest thousandth as needed.)

Answer :

We are given the circumference of the hub cap,

[tex]$$
C = 81.58 \text{ cm},
$$[/tex]

and the value of [tex]$\pi = 3.14$[/tex]. We want to find the area of the hub cap, as well as explain the effect of a smaller circumference on the area.

Step 1. Find the Radius

The circumference of a circle is related to its radius by the formula

[tex]$$
C = 2\pi r.
$$[/tex]

Solving for the radius [tex]$r$[/tex], we have

[tex]$$
r = \frac{C}{2\pi}.
$$[/tex]

Substitute the given values:

[tex]$$
r = \frac{81.58}{2 \times 3.14} \approx \frac{81.58}{6.28} \approx 12.99 \text{ cm}.
$$[/tex]

We round the intermediate value to the nearest thousandth, giving [tex]$r \approx 12.99$[/tex] cm.

Step 2. Calculate the Area

The area [tex]$A$[/tex] of a circle is given by the formula

[tex]$$
A = \pi r^2.
$$[/tex]

Now substitute [tex]$r \approx 12.99$[/tex] cm into the formula:

[tex]$$
A = 3.14 \times \left(12.99\right)^2.
$$[/tex]

Calculating the area:

[tex]$$
\left(12.99\right)^2 \approx 168.87,
$$[/tex]

so

[tex]$$
A \approx 3.14 \times 168.87 \approx 529.88 \text{ cm}^2.
$$[/tex]

Rounding [tex]$529.88$[/tex] to the nearest whole number, we get

[tex]$$
A \approx 530 \text{ cm}^2.
$$[/tex]

Step 3. Explain the Effect of a Smaller Circumference

If the circumference of the hub cap were smaller, the radius would also be smaller because the two are directly related by the equation

[tex]$$
r = \frac{C}{2\pi}.
$$[/tex]

A smaller radius means that when we compute the area

[tex]$$
A = \pi r^2,
$$[/tex]

the result will be significantly smaller, since the radius is squared in the area calculation. This shows that even a modest reduction in the circumference (and thus the radius) can lead to a much larger decrease in the area.

Final Answer:

The radius of the hub cap is approximately [tex]$12.99$[/tex] cm, and its area is about [tex]$530$[/tex] square centimeters. If the circumference were smaller, the area would decrease significantly because it depends on the square of the radius.