Question:medium
If the rate of change in the circumference of a circle is $0.3$ cm/s, then the rate of change in the area of the circle when the radius is $5$ cm is
If the rate of change in the circumference of a circle is $0.3$ cm/s, then the rate of change in the area of the circle when the radius is $5$ cm is
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Chain rule shortcut: $\dfrac{dA}{dt} = \dfrac{dA}{dr}\cdot\dfrac{dr}{dt} = 2\pi r\cdot\dfrac{dr}{dt}$. Find $\dfrac{dr}{dt}$ from the circumference rate first.
Updated On: Apr 8, 2026
- $1.5$ sq cm/s
- $0.5$ sq cm/s
- $5$ sq cm/s
- $3$ sq cm/s
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The Correct Option is A
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