<div style="layout-grid:;
"><div style="text-align: center;"><span class="Apple-style-span" style="font-weight: bold; "><font class="Apple-style-span" color="#FF0000">实验小学北师大版六年级数学上册第一单元测试卷</font></span></div><span style=" letter-spacing:; "></span><br><span style=" font-weight:bold; ">一、填空</span><span style=" font-weight:bold; ">。（19分）</span><span style=" font-weight:bold; "></span><br><br><span>1、画圆时，圆规两脚之间的距离为4厘米，那么这个圆的直径是（ ）厘米，周长是（ ）厘米，面积是（ ）平方厘米。</span><br><br><span>2</span><span>．在等圆中，所有的直径都</span><span>( </span><span> </span><span> )</span><span>，所有的半径都</span><span>( </span><span> </span><span> )</span><span>，直径是半径的</span><span>( )</span><span>。</span><br><br><span>3</span><span>．圆的直径扩大</span><span>3</span><span>倍，它的周长就扩大</span><span>( )</span><span>倍，它的面积就扩大</span><span>( )</span><span>倍。</span><br><br><span>4</span><span>．长方形有</span><span>( )</span><span>条对称轴。正方形有</span><span>( )</span><span>条对称轴，等腰三角形有</span><span>( )</span><span>条对称轴，圆有</span><span>( )</span><span>条对称轴。</span><br><br><span>5</span><span>．在一个边长为</span><span>4</span><span>分米的正方形里，画一个最大的圆，这个圆的直径为</span><span>( </span><span> </span><span> </span><span> </span><span> )</span><span>分米，半径为</span><span>( </span><span> </span><span> )</span><span>分米，周长为</span><span>( </span><span> </span><span> )</span><span>分米，面积为</span><span>( </span><span> </span><span> )</span><span>平方分米。</span><br><br><span>6</span><span>．把一个圆平均分成若干份，可以拼成一个近似于长方形。长方形的长相当于圆的（ ），宽相当于圆的（ ）。</span><br><br><span>7</span><span>．一个半圆形的花坛周长是</span><span>30.84</span><span>米，这个半圆形花坛的面积是</span><span>( </span><span> </span><span> )</span><span>。</span><br><br><span style=" font-weight:bold; ">二、判断。</span><span style=" font-weight:bold; ">（6分）</span><span style=" font-weight:bold; "></span><br><br><span>1</span><span>．一个圆的周长是它半径的</span><span>2</span><span>π倍。</span><span> ( )</span><br><br><span>2</span><span>．一个圆的直径，就是这个圆的对称轴。</span><span> ( )</span><br><br><span>3</span><span>．半圆的周长是与它等半径圆周长的一半。 </span><span> ( )</span><br><br><span>4</span><span>．通过圆心的线段，叫做直径。</span><span> ( )</span><br><br><span>5</span><span>．半径是</span><span>2</span><span>厘米的圆，它的周长和面积相等。</span><span> ( )</span><br><br><span>6</span><span>．一个圆的直径等于一个正方形的边长，那么正方形面积小于圆的面积。</span><span>( )</span><br><br><span style=" font-weight:bold; ">三、选择</span><span style=" font-weight:bold; ">。（7分）</span><span style=" font-weight:bold; "></span><br><br><span>1</span><span>．一个圆的半径乘以π等于这个圆</span><span> ( )</span><span>。</span><br><br><span>(1)</span><span>周长的一半 </span><span> <img src="//www.szxuexiao.com/uploadimages/2012/1113/20121113174246.png?m=0.07664368161931634"> </span><span>(3)</span><span>半圆的周长</span><br><br><span>2</span><span>．在一个长</span><span>6</span><span>厘米，宽</span><span>4</span><span>厘米的长方形内画一个最大的圆，这个圆的面积是</span><span>________</span><span>平方厘米</span><span>( )</span><br><br><span>(1)28.26</span><span> </span><span>(2)19.625</span><span> </span><span>(3)12.56</span><br><br><span>3</span><span>．一个圆的半径</span><span>1</span><span>分米，它的半圆周长是</span><span>________</span><span>分米。</span><span> ( )</span><br><br><span>(1)3.14</span><span> </span><span>(2)4.14</span><span> </span><span>(3)5.14</span><br><br><span>4</span><span>．一个圆的直径扩大</span><span>6</span><span>倍，它的面积就</span><span> ( )</span><br><br><span>(1)</span><span>扩大</span><span>6</span><span>倍 </span><span>(2)</span><span>扩大</span><span>36</span><span>倍 </span><span>(3)</span><span>扩大</span><span>12</span><span>倍</span><br><br><span>5</span><span>．下面三幅图的阴影部分的面积相比较，</span><span>________</span><span>的面积大。</span><span> ( )</span><br><br><span>(1)</span><span>图</span><span>(1)</span><span>大 </span><span>(2)</span><span>图</span><span>(2)</span><span>大 </span><span>(3)</span><span>图</span><span>(3)</span><span>大 </span><span>(4)</span><span>同样大</span><br><br><img src="//www.szxuexiao.com/uploadimages/2012/1113/2012111317438.png?m=0.1547854421660304"><br><br><span>6</span><span>．如图，已知正方形面积是16平方分米，图中圆的面积是</span><span>________</span><span>平方分米。</span><span> ( )</span></div><div style="layout-grid:;
"><br></div><div style="layout-grid:;
"><span></span><img src="//www.szxuexiao.com/uploadimages/2012/1113/20121113174341.png?m=0.29567950894124806"><br><br><span>(1)12.56</span><span> </span><span>(2)6.28</span><span> </span><span>(3)</span><span>15.7 </span><br><br><span>7.一个挂钟的时针长2.5厘米,一昼夜这根时针的尖端走了（ ）</span><br><br><span>A.15.7厘米 B. 31.4厘米 C.78.5厘米</span><br><br><span style=" font-weight:bold; ">四、</span><span style=" font-weight:bold; ">求阴影部分的面积</span><span style=" font-weight:bold; ">。</span><span style=" font-weight:bold; ">（单位：厘米）（8分）</span><span style=" font-weight:bold; "></span><br><br></div><div style="layout-grid:;
"><img src="//www.szxuexiao.com/uploadimages/2012/1113/2012111317446.png?m=0.6951209425460547"><img src="//www.szxuexiao.com/uploadimages/2012/1113/20121113174423.png?m=0.8412719299085438"><br></div><div style="layout-grid:;
"><br><span style=" font-weight:bold; ">五、动手操作（11分）</span><span style=" font-weight:bold; "></span><br><br><span>1、画出一个周长9.42厘米的圆，并用字母标出圆心、半径、直径。（7分）</span><br><br><span>2、</span><span>画下面图形的对称轴</span><span>。</span><span>（能画几条，就画几条）</span><span>（7分）</span><br><br></div><div style="layout-grid:;
"><img src="//www.szxuexiao.com/uploadimages/2012/1113/20121113174524.png?m=0.03721210197545588"><br><span> </span><br><br><span style=" font-weight:bold; ">六、解决问题（共46分，1题10分，其余题每题6分）</span><span style=" font-weight:bold; "></span><br><br><span>1</span><span>、求出下面两图形的周长和面积。</span><span>(</span><span>单位：厘米</span><span>)</span><br><br><img src="//www.szxuexiao.com/uploadimages/2012/1113/20121113174545.png?m=0.7556726022157818"><br><br><span>2</span><span>、</span><span>通过一座桥</span><span>，</span><span>直径是1.2米的车轮需转500圈</span><span>，</span><span>这座桥长多少米？</span><br><br><span>3</span><span>、一个圆形的桌面，直径为80厘米，现在要在桌面上安放一个同样大小的玻璃，求这个桌面玻璃的面积？如果玻璃每平方米价格为100元，这个玻璃要花多少钱？</span><br><br><span>4、</span><span>有大、小两个圆,小圆周长是</span><span>37.68</span><span>米</span><span>，</span><span>大圆直径是小圆直径的2倍</span><span>，</span><span>大圆的面积是多少</span><span>？</span><br><br><span>5、在一个半径为3米的圆形花坛外，围绕一周修一条1米宽的小路，这条小路的面积是多少平方米？</span><br><br><span>6、</span><span>在一个长9厘米，宽6厘米的长方形纸中，剪下一个最大的圆，纸片剩下部分的面积是多少平方厘米？</span><br><br><span>7、</span><span>一只大钟</span><span>，</span><span>它的</span><span>时针</span><span>长40厘米</span><span>。当从中午12时到下午3时，</span><span>这根</span><span>时</span><span>针的尖端所走的路程是多少厘米？</span><br><br></div><div style="layout-grid:;
"><br><br><div style="text-align: center;"><span class="Apple-style-span" style="font-weight: bold; "><font class="Apple-style-span" color="#38761D">实验小学北师大版六年级数学上册第一单元测试卷</font></span></div><span style=" letter-spacing:; "></span><br><span style=" font-weight:bold; ">一、填空</span><span style=" font-weight:bold; ">。（19分）</span><span style=" font-weight:bold; "></span><br><br><span>1、画圆时，圆规两脚之间的距离为4厘米，那么这个圆的直径是（ </span><span style=" font-weight:bold; ">8</span><span> ）厘米，周长是（ </span><span style=" font-weight:bold; ">25.12</span><span> ）厘米，面积是（ </span><span style=" font-weight:bold; ">50.24</span><span> ）平方厘米。</span><br><br><span style=" font-weight:bold; ">思路：圆规两脚间的距离是半径的长度，×2就是直径，直径×3.14就是周长8×3.14，半径的平方×3.14就是面积4</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; ">×3.14</span><span style=" font-weight:bold; "></span><br><br><span>2</span><span>．在等圆中，所有的直径都</span><span>(</span><span style=" font-weight:bold; ">相等</span><span> )</span><span>，所有的半径都</span><span>(</span><span style=" font-weight:bold; ">相等</span><span> )</span><span>，直径是半径的</span><span>(</span><span style=" font-weight:bold; ">2倍</span><span> )</span><span>。</span><br><br><span>3</span><span>．圆的直径扩大</span><span>3</span><span>倍，它的周长就扩大</span><span>( </span><span style=" font-weight:bold; ">3</span><span> )</span><span>倍，它的面积就扩大</span><span>(</span><span style=" font-weight:bold; ">9</span><span> )</span><span>倍。</span><br><br><span style=" font-weight:bold; ">思路：周长扩大的倍数和半径、直径扩大的倍数相同，面积扩大的倍数是半径、直径扩大倍数的平方倍。也可以通过举例找它们之间的关系。</span><span style=" font-weight:bold; "></span><br><br><span>4</span><span>．长方形有</span><span>( </span><span style=" font-weight:bold; ">2</span><span> )</span><span>条对称轴。正方形有</span><span>( </span><span style=" font-weight:bold; ">4</span><span style=" font-weight:bold; "> </span><span>)</span><span>条对称轴，等腰三角形有</span><span>( </span><span style=" font-weight:bold; ">1</span><span> )</span><span>条对称轴，圆有</span><span>( </span><span style=" font-weight:bold; ">无数</span><span> )</span><span>条对称轴。</span><br><br><span style=" font-weight:bold; ">思路：记住等腰三角形有一条对称轴，而等边三角形才有3条。</span><br><br><span>5</span><span>．在一个边长为</span><span>4</span><span>分米的正方形里，画一个最大的圆，这个圆的直径为</span><span>( </span><span style=" font-weight:bold; ">4</span><span> </span><span> )</span><span>分米，半径为</span><span>( </span><span style=" font-weight:bold; ">2</span><span> )</span><span>分米，周长为</span><span>(</span><span style=" font-weight:bold; ">12.56</span><span style=" font-weight:bold; "> </span><span>)</span><span>分米，面积为</span><span>(</span><span style=" font-weight:bold; ">12.56</span><span>)</span><span>平方分米。</span><br><br><span style=" font-weight:bold; ">思路：正方形的边长就是圆的直径，÷2是半径，然后再求周长和面积。</span><span style=" font-weight:bold; "></span><br><br><span>6</span><span>．把一个圆平均分成若干份，可以拼成一个近似于长方形。长方形的长相当于圆的（</span><span style=" font-weight:bold; ">圆周长的一半</span><span>），宽相当于圆的（ </span><span style=" font-weight:bold; "> 半径</span><span>）。</span><br><br><span>7</span><span>．一个半圆形的花坛周长是</span><span>30.84</span><span>米，这个半圆形花坛的面积是</span><span>(</span><span style=" font-weight:bold; "> </span><span style=" font-weight:bold; ">56.52m</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; "> </span><span>)</span><span>。</span><br><br><span style=" font-weight:bold; ">思路：要求圆的面积必须求出圆的半径，根据半圆的周长=πr＋2r，列出方程3.14r＋2r=30.84，解方程求出半径=6m，3.14×</span><span style=" font-weight:bold; ">6</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; ">÷2=56.52</span><span style=" font-weight:bold; ">m</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; ">，部分同学没有÷2或者没写单位。</span><span style=" font-weight:bold; "></span><br><br><span style=" font-weight:bold; ">二、判断。</span><span style=" font-weight:bold; ">（6分）</span><span style=" font-weight:bold; "></span><br><br><span>1</span><span>．一个圆的周长是它半径的</span><span>2</span><span>π倍。</span><span> ( </span><span style=" font-weight:bold; ">√</span><span> )</span><br><br><span>2</span><span>．一个圆的直径，就是这个圆的对称轴。</span><span> ( </span><span style=" font-weight:bold; ">×</span><span> )</span><br><br><span style=" font-weight:bold; ">思路：应该是直径所在的直线。</span><span style=" font-weight:bold; "></span><br><br><span>3</span><span>．半圆的周长是与它等半径圆周长的一半。 </span><span> ( </span><span style=" font-weight:bold; ">×</span><span> )</span><br><br><span style=" font-weight:bold; ">思路：半圆的周长应该是与它等半径圆周长的一半加直径。</span><span style=" font-weight:bold; "></span><br><br><span>4</span><span>．通过圆心的线段，叫做直径。</span><span> ( </span><span style=" font-weight:bold; ">×</span><span> )</span><br><br><span style=" font-weight:bold; ">思路：必须通过圆心，两端都在圆上。</span><span style=" font-weight:bold; "></span><br><br><span>5</span><span>．半径是</span><span>2</span><span>厘米的圆，它的周长和面积相等。</span><span> ( </span><span style=" font-weight:bold; ">×</span><span> )</span><br><br><span style=" font-weight:bold; ">思路：周长和面积意义不同，单位也不同。</span><span style=" font-weight:bold; "></span><br><br><span>6</span><span>．一个圆的直径等于一个正方形的边长，那么正方形面积小于圆的面积。</span><span>( )</span><br><br><span style=" font-weight:bold; ">思路：直径和边长相等时，圆画在正方形的里面，所以正方形面积大于圆的面积。</span><span style=" font-weight:bold; "></span><br><br><span style=" font-weight:bold; ">三、选择</span><span style=" font-weight:bold; ">。（7分）</span><span style=" font-weight:bold; "></span><br><br><span>1</span><span>．一个圆的半径乘以π等于这个圆</span><span> ( </span><span style=" font-weight:bold; ">1</span><span> )</span><span>。</span><br><br><span>(1)</span><span>周长的一半 </span><span> </span><img src="//www.szxuexiao.com/uploadimages/2012/1113/20121113174246.png?m=0.07664368161931634"><span> </span><span>(3)</span><span>半圆的周长</span></div><div style="layout-grid:;
"><br><span style=" font-weight:bold; ">思路：πr就是圆周长的一半。</span><span style=" font-weight:bold; "></span><br><br><span>2</span><span>．在一个长</span><span>6</span><span>厘米，宽</span><span>4</span><span>厘米的长方形内画一个最大的圆，这个圆的面积是</span><span>________</span><span>平方厘米</span><span>( </span><span style=" font-weight:bold; ">3</span><span> )</span><br><br><span>(1)28.26</span><span> </span><span>(2)19.625</span><span> </span><span>(3)12.56</span><br><br><span style=" font-weight:bold; ">思路：宽就是圆的直径。3.14×（4÷2）</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; "></span><br><br><span>3</span><span>．一个圆的半径</span><span>1</span><span>分米，它的半圆周长是</span><span>________</span><span>分米。</span><span> ( </span><span style=" font-weight:bold; ">3</span><span> )</span><br><br><span>(1)3.14</span><span> </span><span>(2)4.14</span><span> </span><span>(3)5.14</span><br><br><span style=" font-weight:bold; ">思路：半圆的周长=πr＋2r，3.14×1＋2×1=5.14</span><span style=" font-weight:bold; "></span><br><br><span>4</span><span>．一个圆的直径扩大</span><span>6</span><span>倍，它的面积就</span><span> ( </span><span style=" font-weight:bold; ">2</span><span> )</span><br><br><span>(1)</span><span>扩大</span><span>6</span><span>倍 </span><span>(2)</span><span>扩大</span><span>36</span><span>倍 </span><span>(3)</span><span>扩大</span><span>12</span><span>倍</span><br><br><span style=" font-weight:bold; ">思路：同填空题第三小题。</span><span style=" font-weight:bold; "></span><br><br><span>5</span><span>．下面三幅图的阴影部分的面积相比较，</span><span>________</span><span>的面积大。</span><span> ( </span><span style=" font-weight:bold; ">4</span><span> )</span><br><br><span>(1)</span><span>图</span><span>(1)</span><span>大 </span><span>(2)</span><span>图</span><span>(2)</span><span>大 </span><span>(3)</span><span>图</span><span>(3)</span><span>大 </span><span>(4)</span><span>同样大</span><br><br></div><div style="layout-grid:;
"><img src="//www.szxuexiao.com/uploadimages/2012/1113/2012111317438.png?m=0.1547854421660304"></div><div style="layout-grid:;
"><span style=" font-weight:bold; ">思路：阴影部分的面积都可以看成正方形的面积－圆的面积</span><span style=" font-weight:bold; "></span><br><br><span>6</span><span>．如图，已知正方形面积是16平方分米，图中圆的面积是</span><span>________</span><span>平方分米。</span><span> ( </span><span style=" font-weight:bold; ">1</span><span> )</span><br><br><span>(1)12.56</span><span> </span><span>(2)6.28</span><span> </span><span>(3)</span><span>15.7 </span><img src="//www.szxuexiao.com/uploadimages/2012/1113/20121113174341.png?m=0.29567950894124806"> </div><div style="layout-grid:;
"><br><span style=" font-weight:bold; ">思路：根据正方形的面积是16可知边长应为4分米也就是直径是4分米，然后再求面积</span><span style=" font-weight:bold; "></span><br><br><span>7.一个挂钟的时针长2.5厘米,一昼夜这根时针的尖端走了（ </span><span style=" font-weight:bold; ">B</span><span> ）</span><br><br><span>A.15.7厘米 B. 31.4厘米 C.78.5厘米</span><br><br><span style=" font-weight:bold; ">思路：时针的长度是半径，知道半径求周长，一昼夜走两圈，也就是周长×2</span><span style=" font-weight:bold; "></span><br><br><span style=" font-weight:bold; ">四、</span><span style=" font-weight:bold; ">求阴影部分的面积</span><span style=" font-weight:bold; ">。</span><span style=" font-weight:bold; ">（单位：厘米）（8分）</span><span style=" font-weight:bold; "></span><br><br><img src="//www.szxuexiao.com/uploadimages/2012/1113/2012111317446.png?m=0.6951209425460547"><img src="//www.szxuexiao.com/uploadimages/2012/1113/20121113174423.png?m=0.8412719299085438"><br><span style=" font-weight:bold; ">（1）思路：用正方形的面积－圆的面积（四个空白的扇形可以拼成一个圆）列式：10×10－3.14×（10÷2）</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; ">=21.5</span><span style=" font-weight:bold; "></span><br><br><span style=" font-weight:bold; ">（2）阴影部分的面积可以看成两个圆的面积3.14×（4÷2）</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; ">×2=25.12</span><span style=" font-weight:bold; "></span><br><br><span style=" font-weight:bold; ">五、动手操作（11分）</span><span style=" font-weight:bold; "></span><br><br><span>1、画出一个周长9.42厘米的圆，并用字母标出圆心、半径、直径。（7分）</span><br><br><span style=" font-weight:bold; ">思路：根据9.42÷3.14÷2=1.5可知应该画一个半径为1.5cm的圆。，再用字母标出圆心、半径、直径</span><span style=" font-weight:bold; "></span><br><br><span style=" z-index:1; left:0px; "></span><span>2、</span><span>画下面图形的对称轴</span><span>。</span><span>（能画几条，就画几条）</span><span>（7分）</span><br><br><img src="//www.szxuexiao.com/uploadimages/2012/1113/2012111317513.jpg?m=0.6044029348995537"><br><br><span style=" font-weight:bold; ">(1)思路：3条应该通过圆心和另外两个圆的交叉部分，假如把三个圆心连起来就是一个等边三角形，实际上也就是给这个等边三角形画对称轴。</span><span style=" font-weight:bold; "></span><br><br><span style=" font-weight:bold; ">（2）思路：有4条，实际上就是给正方形画对称轴。</span><span style=" font-weight:bold; "></span><br><br><span style=" font-weight:bold; ">六、解决问题（共46分，1题10分，其余题每题6分）</span><span style=" font-weight:bold; "></span><br><br><span>1</span><span>、求出下面两图形的周长和面积。</span><span>(</span><span>单位：厘米</span><span>)</span><br><br><img src="//www.szxuexiao.com/uploadimages/2012/1113/20121113175124.png?m=0.11690713837742805"><br><br><span style=" font-weight:bold; ">（1）思路：周长：3.14×12=37.68 面积：3.14×（12÷2）</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; ">=113.04</span><span style=" font-weight:bold; "></span><br><br><span style=" font-weight:bold; ">（2）思路：周长：分成两部分：圆周长的一半5×2×3.14÷2=15.7和一个正方形5×4=20,15.7＋20=35.7。面积：分成两部分：半圆的面积3.14×5</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; ">÷2=39.25和一个正方形5×5=25，然后39.25＋25=64.25</span><span style=" font-weight:bold; "></span><br><br><span>2</span><span>、</span><span>通过一座桥</span><span>，</span><span>直径是1.2米的车轮需转500圈</span><span>，</span><span>这座桥长多少米？</span><br><br><span style=" font-weight:bold; ">思路：3.14×1.2×500（结果1884）</span><span style=" font-weight:bold; "></span><br><br><span>3</span><span>、一个圆形的桌面，直径为80厘米，现在要在桌面上安放一个同样大小的玻璃，求这个桌面玻璃的面积？如果玻璃每平方米价格为100元，这个玻璃要花多少钱？</span><br><br><span style=" font-weight:bold; ">思路：注意单位换算和40</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; ">=40×40＝1600不等于160。80÷2=40,3.14×40</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; ">=3.14×1600=5024cm</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; ">,5024cm</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; ">=0.5024m</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; ">，0.5024×100=50.24元</span><span style=" font-weight:bold; "></span><br><br><span>4、</span><span>有大、小两个圆,小圆周长是</span><span>37.68</span><span>米</span><span>，</span><span>大圆直径是小圆直径的2倍</span><span>，</span><span>大圆的面积是多少</span><span>？</span><br><br><span style=" font-weight:bold; ">思路：37.68÷3.14等于小圆的直径，再×2是大圆的直径，再÷2是大圆的半径，3.14×12</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; ">=452.16</span><span style=" font-weight:bold; "></span><br><br><span>5、在一个半径为3米的圆形花坛外，围绕一周修一条1米宽的小路，这条小路的面积是多少平方米？</span><br><br><span style=" font-weight:bold; ">思路：这道题求销路的面积就是求圆环的面积3.14×（3＋1）</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; ">－3.14×3</span><span style=" font-weight:bold; vertical-align:super; ">2</span><span style=" font-weight:bold; "></span><br><br><span>6、</span><span>在一个长9厘米，宽6厘米的长方形纸中，剪下一个最大的圆，纸片剩下部分的面积是多少平方厘米？</span><br><br><span style=" font-weight:bold; ">思路：最大的圆的直径应该是长方形的宽，然后用长方形的面积－圆的面积</span><span style=" font-weight:bold; "></span><br><br><span>7、</span><span>一只大钟</span><span>，</span><span>它的</span><span>时针</span><span>长40厘米</span><span>。当从中午12时到下午3时，</span><span>这根</span><span>时</span><span>针的尖端所走的路程是多少厘米？</span><br><br><span style=" font-weight:bold; ">思路：时针相当于圆的半径，中午12时到下午3时，时针所走的路程相当于一个圆的四分之一，所以求出圆的面积再÷4或乘四分之一。部分同学没有用40×2或最后当成了3圈去乘3这是不对的。</span><span style=" font-weight:bold; "></span><br><br><br></div>
六年级上