What is the area A of the cross section of the column?

Question

A building engineer analyzes a concrete column with a circular cross section. The circumference of the column is 18π meters.

Give your answer in terms of pi

Answer 1

Since the circumference is 18π, 2πr = 18π

2r = 18. So, r = 9

Area = πr² = 81π ≈ 254.47 m

Answer 2

area of a circle is r^2pi.

circ " " dpi

18n/pi=5.73n

(2.864n)^2*3.14=8.207n*3.14=25.783n