图中梯形ABCD的面积是90平方厘米,AC=3AO,那么阴影部分的面积是多少平方厘米?

图中梯形ABCD的面积是90平方厘米,AC=3AO,那么阴影部分的面积是多少平方厘米?
图中梯形ABCD的面积是90平方厘米,AC=3AO,那么阴影部分的面积是多少平方厘米?

图中梯形ABCD的面积是90平方厘米,AC=3AO,那么阴影部分的面积是多少平方厘米?
由同高,底的比值为1：2可知
四个三角形的面积关系如下
BOC=2DOC=2AOB=4AOD
所以梯形的面积是三角形AOD面积的9倍
AOD面积是10平方厘米

10平方厘米

等于10 易证三角形ADO相似于三角形CBO 则AD/BC=AO/CO AC=3AO所以OC=2AO 所以AO/OC=1/2=AD/BC 根据相似三角形的高比等于相似比，得 h三角形AOD=-2h三角形COB 设AD=X BC=2X h三角形AOD=Y h三角形COB=2Y 梯形的面积为 3X*3Y*1/2=90 则 1/2XY= 10 ...

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等于10 易证三角形ADO相似于三角形CBO 则AD/BC=AO/CO AC=3AO所以OC=2AO 所以AO/OC=1/2=AD/BC 根据相似三角形的高比等于相似比，得 h三角形AOD=-2h三角形COB 设AD=X BC=2X h三角形AOD=Y h三角形COB=2Y 梯形的面积为 3X*3Y*1/2=90 则 1/2XY= 10 S三角形AOD=1/2XY=10

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Some of you may have read David Byrne's recent review in The New York,Chanel Handbags Online
Times of Pedaling Revolution: How Cyclists Are Changing American
Ci...

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Some of you may have read David Byrne's recent review in The New York,Chanel Handbags Online
Times of Pedaling Revolution: How Cyclists Are Changing American
Cities. And some of you probably know that the Talking Heads frontman,
a long-time bike advocate, has his own biking book coming out this
September called Bicycle Diaries.
An advanced copy of the book arrived in our mailbox today. At 294
pages, and filled with postcard-like black-and-white photos, Bicycle
Diaries is a first-person account of Mr. Byrne's experiences biking
through various cities around the world, from London (chapter 1) to
Istanbul (chapter 3) to San Fransisco (chapter 8) and,PUMA Tennis Shoes, of course, New
York. (It's worth noting,UGG Slippers, as the ledes of both the book and his Times
review illustrate, that Mr. Byrne likes to point out he's been riding a
bike around New York as his principal means of transportation since the
early '80s. He's also known to do press ops for bike-oriented
Department of Transportation initiatives.)
Here's what the accompanying press release has to say:
As Byrne pedals through metropolises from Berlin to Buenos Aires ... he
sees economics revealed in shop fronts and history in door frames. With
a highly personal mixture of humor and curiosity, he records his
thoughts on globalization, world music, urban planning, fashion,
policy, architecture, cultural dislocation, and much more. Byrne
explains why efforts to increase bicyle use may solve some of the
world's pressing transportation and energy concerns, and in an
appendix, offers tips on bike security, rider safety, and clothing and
listings of bicycle activist organizations across the country.
Incidentally, The Fader has a three-part video slideshow of Mr. Byrne's
office on its Web site. Thanks to PSFK for the tip.

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