1. ## Need help with confirming answers

Two oil tankers crash in the Pacific ocean. The spreading oil slick has a
circular shape, and the radius of the circle is increasing at 200
meters per hour.

a) Express the radius of the spill, r, as a power function of time, t,
in hours since the crash.

b) Express the area of the spill, A, as a power function of time, t.

For a) would the formula be f(r) = 200t^2?
For b) would the formula be f(a) = pi(200t)^2?

Thanks for the help.

2. Originally Posted by krzyrice
Two oil tankers crash in the Pacific ocean. The spreading oil slick has a
circular shape, and the radius of the circle is increasing at 200
meters per hour.

a) Express the radius of the spill, r, as a power function of time, t,
in hours since the crash.

b) Express the area of the spill, A, as a power function of time, t.

For a) would the formula be f(r) = 200t^2?
For b) would the formula be f(a) = pi(200t)^2?

Thanks for the help.
a) You should know that $D = TV$.

In this case, D is the radius, T is the time, V is the speed.

$r = 200t$, where $r$ is measured in metres and $t$ in hours.

b) You should know that $A = \pi r^2$

So $A = \pi (200t)^2$

$A = 400 \pi t^2$.

3. I thought it was A = 40,000(pi)(t^2) since you have to distribute the power of 2 in pi(200t)^2

4. Originally Posted by krzyrice
I thought it was A = 40,000(pi)(t^2) since you have to distribute the power of 2 in pi(200t)^2
Yes, that's a typo.