An oil slick is expanding as a circle. The radius of the circle is increasing at the rate of 20 meters per day. Express the area of the circle as a function of d, the number of days elapsed.
Accepted Solution
A:
The circle expands it radius 20m each day. From this description you can get this equation: r=0+ 20*d r=20d
The oil slick expands as a circle and the formula for circle area is [tex] \pi [/tex] r^2. If you insert the first equation into this equation you will got: circle area = [tex] \pi [/tex] r^2 circle area = [tex] \pi [/tex] (20d)^2 circle area = [tex] \pi [/tex] 400*d^2