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NDA2020MathematicsApplication of DerivativesActual

The radius of a circle is increasing at the rate of 0.7 ~cm / sec . What is the rate of increase of its circumference?

Options

  1. A4.4 ~cm / sec
  2. B8.4 ~cm / sec
  3. C8.8 ~cm / sec
  4. D15.4 ~cm / sec

Correct answer

A. 4.4 ~cm / sec

Step-by-step solution

Circumference of a circle C=2 r Differentiating both sides w.r.t. time (t) . d c d t =2 d r d t =2 (0.7)=1.4 =1.4 22 7 =4.4 ~cm / sec

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