Here barrel of tomato sauce has spilled on a tile floor.
The function [tex]r(t)=2t[/tex] represents how the sauce is flowing, where, 't' represents time in minutes, and 'r' represents how far the sauce is spreading.
The spilled sauce is creating a circular pattern on the tile and the area of pattern is expressed as [tex]A(r)=\pi\times r^2[/tex]
A. Now we have to find the area of circle of spilled sauce as a function of time:
[tex]A(r(t))[/tex].
Now, we know that
[tex]A=\pi r^2[/tex]
and [tex]r(t)=2t[/tex]
plugging the value of 'r' as function of time in the area of the pattern, we get:
[tex]A(r(t))=\pi \times (2t)^2=\pi \times 4t^2=4\pi t^2[/tex]
So the area of the circular pattern as a function of time is given as:
[tex]A=4 \pi t^2[/tex]
B. We have to find how large is the area of spilled sauce after 5 minutes.
plugging the value of 't' in the equation of the area as a function of time, [tex]t=5[/tex]
we get:
[tex]A(t)=4 \times \pi \times (5)^2=4 \pi \times 25=100 \pi=314[/tex]
(we have taken [tex]\pi=3.14[/tex])
Therefore, [tex]A=314[/tex] square units