express the area of the circle.

Question

An oil slick is expanding as a circle. The radius of the circle is increasing at the rate of 22 meters per day. Express the area of the circle as a function of d, the number of days elapsed.

Answer 1

d = number of days since the oil slick started

 

r = radius in d days = 22d

 

A(d) = area of oil slick in d days = π(22d)²

 

A(d) = 484πd²

 

Answer 2

A = πr²

A = π(r + 22d)²