作者matmoki (户田最高)
看板trans_math
标题Re: [微分] 应用题
时间Sun Nov 30 22:26:19 2008
※ 引述《victor7935 (victor)》之铭言：
: The base of an isoceles triangle is 6 feet.
: Given that the altitude is 4 feet and increasing
: at the rate of 2 inches per minute,at what rate is the
: vetex angle changing ?
: 不大懂题目的意思...
: 帮忙一下罗! Thanks!
高L 一半底边S
1 feet = 12 inch ......
tan(
θ/2)=S/L θ=arctan(S/L)
*2
-S(dL/dt)
-----2----
L
dθ/dt = -------2----
*2 = -6
*2/(25*12) = -0.04
1 + S
--2-
L
--
※ 发信站: 批踢踢实业坊(ptt.cc)
◆ From: 122.117.188.214
1F：→ victor7935:把角度拆成一半算..变化率没差?140.123.221.147 11/30 23:35
2F：推 victor7935:了解....原来是单位!!140.123.221.147 11/30 23:44
3F：→ victor7935:谢谢!!140.123.221.147 11/30 23:44
※ 编辑: matmoki 来自: 122.117.188.214 (12/01 00:18)