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ID:52294567
大小:1.50 MB
页数:17页
时间:2020-04-04
《勾股定理[第2课时]勾股定理课件.ppt》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、17.1勾股定理的应用第2课时人教版初中数学八年级下册Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.一回顾交流,小测评估1已知直角三角形ABC的三边为a,b,c,∠C=90°,则a,b,c三者之间的关系是。Eval
2、uationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.2、若一个直角三角形两条直角边长是3和2,那么第三条边长是多少?3、若一个直角三角形两条边长是3和2,那么第三条边长是多少?要注意分类讨论的思想的应用噢!Evaluationonl
3、y.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.4、有一个边长为50dm的正方形洞口,想用一个圆盖去盖住这个洞口,圆的直径至少多长?(结果保留整数)50dmABCD解:在Rt△ABC中,∠B=90°由勾股定理得:Evaluationonly.Cr
4、eatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.5.已知如图所示,等边三角形ABC的边长为8:(1)求高AD的长(2)求这个三角形的面积(答案可保留根号)Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5C
5、lientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.课中探究探究1如图,一个3m长的梯子AB,斜靠在一竖直的墙AO上,这时AO的距离为2.5m,如果梯子的顶端A沿墙下滑0.5m,那么梯子底端B也外移0.5m吗?在Rt△AOB中,OB==.在Rt△COD中,OD==.BD=.梯子的顶端沿墙下滑0.5m,梯子底端外移____m
6、Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.荷花问题平平湖水清可鉴,面上半尺生红莲;出泥不染亭亭立,忽被强风吹一边;渔人观看忙向前,花离原位二尺远;能算诸君请解题,湖水如何知深浅.0.5xx+0.52答:湖水深3.7
7、5尺.探究2:可用勾股定理建立方程.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.执竿进屋笨人持竿要进屋,无奈门框栏住竹,横多四尺竖多二,没法急得放声哭。有个邻居聪明者,教他斜竿对两角,
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