1. A circular ripple on a pond is radiating outwards at rate 2ft/s.
a) At what rate(ft/s) is the circumference increasing when the radius is 10ft?
b) At what rate (ft^2/s) is the area increasing when the radius is 10 ft?
math problem
2010-09-22 5:56 pm
回答 (1)
2010-09-22 6:52 pm
✔ 最佳答案
Let r,l and A be radius, circumference and area of the circular ripplea)
l=2pi*r
differentiate both sides w.r.t. t
dl/dt=2pi*dr/dt=2pi*(2)=4pi ft/s
b)
A=pi*r^2
differentiate both sides w.r.t. t
dA/dt=2pi*r*dr/dt=2pi*10*2=40pi ft/s
收錄日期: 2021-04-22 00:51:22
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100922000051KK00235