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CUET · MATHS · PYQ PAPER 2025

The rate of change of the area of a circle with respect to its radius r, when r = 3 cm is :

  1. A \(6 \pi cm^2 / cm\)
  2. B \(4 \pi cm^2 / cm\)
  3. C \(2 \pi cm^2 / cm\)
  4. D \(3 \pi cm^2 / cm\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(6 \pi cm^2 / cm\)

Step-by-step Solution

Detailed explanation

\(A = \pi r^2\) \(\frac{dA}{dr} = 2\pi r\) \(\frac{dA}{dr}\Big|_{r=3} = 2\pi (3) = 6\pi\) \(6\pi cm^2 / cm\)