Question

find the circumference and area of each circle. round to the nearest tenth. (one decimal place)
5.
6.

1. c=

a=

1. c=

a=

Explanation:

Problem 5:

Step1: Find the circumference

The formula for the circumference of a circle is \(C = 2\pi r\), where \(r = 11\) ft.

$$ C=2\times\pi\times11\approx2\times3.14\times11 = 69.1 $$

Step2: Find the area

The formula for the area of a circle is \(A=\pi r^{2}\), where \(r = 11\) ft.

$$ A=\pi\times11^{2}\approx3.14\times121 = 379.9 $$

Problem 6:

Step1: Find the radius

Given the diameter \(d = 9\) mm, the radius \(r=\frac{d}{2}=\frac{9}{2}=4.5\) mm.

Step2: Find the circumference

Using \(C = 2\pi r\), with \(r = 4.5\) mm.

$$ C=2\times\pi\times4.5\approx2\times3.14\times4.5=28.3 $$

Step3: Find the area

Using \(A=\pi r^{2}\), with \(r = 4.5\) mm.

$$ A=\pi\times(4.5)^{2}\approx3.14\times20.25 = 63.6 $$

Answer:

1. \(C\approx69.1\) ft, \(A\approx379.9\) ft²
2. \(C\approx28.3\) mm, \(A\approx63.6\) mm²