Answer:
-94.2 [tex]cm^2/min[/tex]
Step-by-step explanation:
Rate of change of radius = -5 cm per minute (as it is decreasing)
Radius of circle = 6 cm
Formula for area of Area:
[tex]A = \pi r^2[/tex]
Formula for differentiation of [tex]y = x^n[/tex]:
[tex]\dfrac{dy}{dt} = nx^{n-1}\dfrac{dx}{dt}[/tex]
Differentiating area w.r.to [tex]t[/tex]:
[tex]\dfrac{dA}{dt} = 2\pi r\dfrac{dr}{dt}[/tex]
Putting the values, [tex]r = 6, \frac{dr}{dt} = -5[/tex] cm per minute.
[tex]\dfrac{dA}{dt} = 6\pi \times (-5)\\\Rightarrow \dfrac{dA}{dt} = -30 \times 3.14\\\Rightarrow \dfrac{dA}{dt} = -94.2\ cm^2/min[/tex]
Negative sign indicates that area is decreasing.
Rate of change of area is -94.2 [tex]cm^2/min[/tex].
