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Ex 6.1,17 (MCQ) - Chapter 6 Class 12 Application of Derivatives (Term 1)
Last updated at Aug. 9, 2021 by Teachoo
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Transcript
Ex 6.1, 17 The rate of change of the area of a circle with respect to its radius r at r = 6 cm is (A) 10π (B) 12π (C) 8π (D) 11πLet r be the radius of circle & A be the area of circle We need to find Rate of change of Area of circle w.r.t to radius at π = 6 i.e. we need to find π π¨/π π at π = 6 We know that Area of circle = A = π π^2 Differentiating w.r.t π ππ΄/ππ=π(ππ^2 )/ππ ππ΄/ππ=π π(π^2 )/ππ ππ΄/ππ=π . 2r π π¨/π π=ππ π Putting π = 6 γππ΄/ππβγ_(π = 6" " )=2π(6) γππ΄/ππβγ_(π = 6" " )=πππ Hence, Correct answer is B
