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MHT CET202014 Oct 2020Morning ShiftMathematicsDifferential EquationsActual

If the radius of a circle increases at the rate of 7 ~cm / sec , then the rate of increase of its area after 10 minutes is

Options

  1. A1,84,800 ~cm ² / sec
  2. B1,64,800 ~cm ² / sec
  3. C1,88,400 ~cm ² / sec
  4. D1,68,400 ~cm ² / sec

Correct answer

A. 1,84,800 ~cm ² / sec

Step-by-step solution

aligned d d t &=7 ~cm / sec . A &= ² d A d t &=2 d d t -(1) Radius after 10 minutes ; & =70 ~cm 60 ~cm d A d t &=2 22 7 70 7 60[ Put in (1)... &=1,84,800 ~cm ² / sec . aligned

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