Duration: 1:55

46 views

0

A stone is dropped into a quiet lake and waves
P move in circles spreading out radially at the

W speed of \( 5 \mathrm{~cm} / \mathrm{s} \). At the instant when the radius of the circular wave is \( 8 \mathrm{~cm} \), how fast is the enclosed area increasing?
(1) \( 80 \pi \mathrm{cm}^{2} / \mathrm{s} \)
(2) \( 90 \pi \mathrm{cm}^{2} / \mathrm{s} \)
(3) \( 85 \pi \mathrm{cm}^{2} / \mathrm{s} \)
(4) \( 40 \pi \mathrm{cm}^{2} / \mathrm{s} \)
📲PW App Link - https://bit.ly/YTAI_PWAP
🌐PW Website - https://www.pw.live