Manipal MET2018MathematicsApplication of Derivatives
If the rate of change in the circumference of a circle of 0.3 ~cm / s , then the rate of change in the area of the circle when the radius is 5 cm , is
Options
- A1.5 sq cm / s
- B0.5 sq cm / s
- C5 sq cm / s
- D3 sq cm / s
Correct answer
A. 1.5 sq cm / s
Step-by-step solution
Circumference of circle, C=2 r aligned & d C d t =2 d r d t & 0.3 2 = d r d t aligned ( d C d t =0.3 ~cm / s given ) 1 Now, A= r^2 array cc & d A d t =2 r d r d t d A d t =r 0.3 & [ d A d t ]_ r=5 =5 0.3=1.5 sq ~cm / s array