Question

A building engineer analyzes a concrete column with a circular cross section. The circumference of the column is 18 \pi18π18, pi meters. What is the area AAA of the cross section of the column? Give your answer in terms of pi. A =A=A, equals \text{ m}^2 m 2 start text, space, m, end text, squared

Answer 1

81pi

Explanation:

Answer 2

`A=81\pi $ m^2`

Explanation:

Circumference of the column
`=18\pi $ meters`

Circumference of a circle
`=2\pi r`

Therefore:

`2\pi r =18\pi $ meters\\2r=18\\r=18 / 2\\$Radius, r=9 meters`

Area of a Circle
`=\pi r^2`

Since radius of the cross section of the column =9 meters

Area of the cross section of the column

`=\pi *9^2\\=81\pi $ m^2`