07glli 乱答一气加用软件,楼主明鉴
先看y=cosx和y=1-cosx的交点
cosx=1-cosx
cosx=1/2
即x=pi/3
即由图像可知[0,pi/3)上cosx>1-cosx
(pi/3,pi]上1-cosx>cosx
所以area=积分<0->pi/3> [cosx-(1-cosx)]dx + 积分<pi/3->pi> [(1-cosx)-cosx]dx
=积分<0->pi/3> [2cosx-1]dx + 积分<pi/3->pi> [1-2cosx]dx
=2sinx-x |<0->pi/3> + (x-2sinx)|<pi/3->pi>
=2(根号3/2-0)-(pi/3-0)+(pi-pi/3)-2(0-根号3/2)
=2根号3+pi/3
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A=积分<0->10> b(t)-d(t) dt
=积分<0->10> 2200e^(0.022t) dt - 积分<0->10> 1520e^(0.017t) dt
=2200e^(0.022t)/.022 |<0->10> - 1520e^(0.017t)/.017|<0->10>
=100000(e^.22-1)-(1520000/17)(e^.17-1)
This area represents the increase of the population (birth-death)
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积分<50->100> R'(x)-C'(x) dx
=积分<50->100> R'(x) dx -积分<50->100> C'(x) dx
=[R(100)-R(50)]-[C(100)-C(50)]
This area represents the profit difference between selling 100 and 50 units of products
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(a)
Suppose the height is x, then the side length of the horizontal crosssection is b-[(b-a)/h]*x
The volume is
积分<0->h> {b-[(b-a)/h]*x}^2 dx
=积分<0->h> b^2-[2b(b-a)/h]x+[(b-a)^2/h^2]x^2 dx
=b^2h-b(b-a)h+(b-a)^2h/3
=abh+(b-a)^2/2
(b)a=b
V=a^2h, the volume is actually a rectangle
(c)a=0
V=b^2h/3, the volume is actually a pyramid
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Suppose the height is x, then the radius of the circle is r-(x/h)r
The volume is
V=积分<0,h> pi [r-(x/h)r]^2 dx
=pir^2积分<0,h>[1-2x/h+(x/h)^2]dx
=pi r^2 [h-h+h/3]
=pi*r^2h/3
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