
Ex 6.1
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Ex 6.1,17 (MCQ) Deleted for CBSE Board 2022 Exams You are here
Ex 6.1, 18 (MCQ) Important Deleted for CBSE Board 2022 Exams
Last updated at Aug. 9, 2021 by Teachoo
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