小学教育网 发表于 2018-12-7 23:15:52

人教版六年级上册《圆的周长和面积》数学教案

人教版六年级上册《圆的周长和面积》数学教案
          教学目标:
       
          同步教学知识内容
       
          个性化学习问题解决
       
          教学重点:
       
          运用圆的面积公式计算公式解决实际问题。理解圆的面积计算公式的推到过程。
       
          教学过程:
       
          一、圆面积的计算公式
       
          1. 圆所占面积的大小叫圆的面积。
       
          2. 圆的面积的大小与半径的长短有关。
       
          3. 面积=3.14乘半径的平方 字母表示为( )
       
          二、圆面积的应用
       
          1. 应用一 已知圆的直径,求圆的面积。
       
          分析: 因为圆的面积公式是 面积=3.14乘半径的平方,所以我们要先求出圆的半径,半径=直径/2
       
          2. 应用二 已知圆的周长,求圆的面积。
       
          分析: 通过圆周长的公式可以求出圆的直径,直径=周长/π 半径=直径/2,再用面积公式进行计算。 3. 应用三 圆的半径与圆的直径,周长,面积的关系。
       
          分析; 当圆的半径扩大2倍,那么
       
          圆的直径扩大2倍
       
          圆的周长扩大2倍
       
          圆的面积扩大2×2倍
       
          当圆的半径扩大3倍,那么
       
          圆的直径(   )
       
          圆的周长(   )
       
          圆的面积(   )

jzfive 发表于 2018-12-8 00:46:03


       
          例1.求阴影部分的面积。(单位:厘米)
       
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
          解:这是最基本的方法:1/4圆面积减去等腰直角三角形的面积
http://www.aoshu.com/e/20181202/data:image/png;base64,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
          例2.正方形面积是7平方厘米,求阴影部分的面积。(单位:厘米)
       
http://www.aoshu.com/e/20181202/data:image/png;base64,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
          解:这也是一种最基本的方法用正方形的面积减去1/4圆的面积。
       
          设圆的半径为 r,因为正方形的面积为7平方厘米,所以 =7
       
          所以阴影部分的面积为:
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查看完整版本: 人教版六年级上册《圆的周长和面积》数学教案