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单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,确定起跑线,人教版六年级数学上册第四单元,1,2,3,4,5,6,7,8,直径,(m),圆周长,(m),跑道全长,(m),注：,取,3.14159,。结果保留三位小数。,228.079,235.933,243.787,251.641,259.495,267.349,275.203,283.057,399.999,407.853,415.707,423.561,431.415,439.269,447.123,454.977,72.6,75.1,77.6,80.1,82.6,85.1,87.6,90.1,7.854,7.854,7.854,7.854,7.854,7.854,7.854,1,2,3,4,5,6,7,8,直径,(m),圆周长,(m),周长的,一半,(m),注：,取,3.14159,。结果保留三位小数。,228.079,235.933,243.787,251.641,259.495,267.349,275.203,283.057,114.040,117.967,121.894,125.821,129.748,133.675,137.602,141.529,72.6,75.1,77.6,80.1,82.6,85.1,87.6,90.1,3.927,3.927,3.927,3.927,3.927,3.927,3.927,12345678,85.96m,72.6m,85.96m,72.6m,1.25m,1.25m,1.25m,85.96m,72.6m,1.25m,1.25m,1.25m,85.96m,72.6m,第一道,直径：,周长：,全长：,72.6m,72.63.14159228.08,（,m,）,85.962,228.08=400,（,m,）,1,2,3,4,5,6,7,8,直径,(m),周长,(m),全长,(m),72.6,228.08,400,注：,取,3.14159,85.96m,72.6m,第一道,直径：,周长：,全长：,72.6m,228.08m,400m,第二道,直径：,周长：,全长：,72.6,1.25,1.25=75.1,（,m,）,75.1,3.14159235.93,（,m,）,85.962,235.93,=407.85,（,m,）,1.25m,1.25m,1,2,3,4,5,6,7,8,直径,(m),周长,(m),全长,(m),72.6,228.08,400,75.1,235.93,407.85,注：,取,3.14159,85.96m,72.6m,第二道,直径：,周长：,全长：,75.1m,235.93m,407.85m,第三道,直径：,周长：,全长：,75.1,1.25,1.25=77.6,（,m,）,77.6,3.14159243.79,（,m,）,85.962,243.79,=415.71,（,m,）,1.25m,1.25m,75.1m,1,2,3,4,5,6,7,8,直径,(m),周长,(m),全长,(m),72.6,228.08,400,75.1,235.93,407.85,77.6,243.79,415.71,注：,取,3.14159,85.96m,72.6m,第三道,直径：,周长：,全长：,77.6m,243.79m,415.71m,第四道,直径：,周长：,全长：,77.6,1.25,1.25=80.1,（,m,）,80.1,3.14159251.64,（,m,）,85.962,251.64,=423.56,（,m,）,1.25m,1.25m,77.6m,1,2,3,4,5,6,7,8,直径,(m),周长,(m),全长,(m),72.6,228.08,400,75.1,235.93,407.85,77.6,243.79,415.71,80.1,251.64,423.56,注：,取,3.14159,85.96m,72.6m,第四道,直径：,周长：,全长：,80.1m,251.64m,423.56m,第五道,直径：,周长：,全长：,80.1,1.25,1.25=82.6,（,m,）,82.6,3.14159259.50,（,m,）,85.962,259.5,=431.42,（,m,）,1,2,3,4,5,6,7,8,直径,(m),周长,(m),全长,(m),72.6,228.08,400,75.1,235.93,407.85,77.6,243.79,415.71,80.1,251.64,423.56,82.6,259.5,431.42,注：,取,3.14159,85.96m,72.6m,第五道,直径：,周长：,全长：,82.6m,259.5m,431.42m,第六道,直径：,周长：,全长：,82.6,1.25,1.25=85.1,（,m,）,85.1,3.14159267.35,（,m,）,85.962,267.35,=439.27,（,m,）,1,2,3,4,5,6,7,8,直径,(m),周长,(m),全长,(m),72.6,228.08,400,75.1,235.93,407.85,77.6,243.79,415.71,80.1,251.64,423.56,82.6,259.5,431.42,85.1,267.35,439.27,注：,取,3.14159,85.96m,72.6m,第六道,直径：,周长：,全长：,85.1m,267.35m,439.27m,第七道,直径：,周长：,全长：,85.1,1.25,1.25=87.6,（,m,）,87.6,3.14159275.20,（,m,）,85.962,275.2,=447.12,（,m,）,1,2,3,4,5,6,7,8,直径,(m),周长,(m),全长,(m),72.6,228.08,400,75.1,235.93,407.85,77.6,243.79,415.71,80.1,251.64,423.56,82.6,259.5,431.42,85.1,267.35,439.27,87.6,275.2,447.12,注：,取,3.14159,85.96m,72.6m,第七道,直径：,周长：,全长：,87.6m,275.2m,447.12m,第八道,直径：,周长：,全长：,87.6,1.25,1.25=90.1,（,m,）,90.1,3.14159283.06,（,m,）,85.962,283.06,=454.98,（,m,）,1,2,3,4,5,6,7,8,直径,(m),周长,(m),全长,(m),72.6,228.08,400,75.1,235.93,407.85,77.6,243.79,415.71,80.1,251.64,423.56,82.6,259.5,431.42,85.1,267.35,439.27,87.6,275.2,447.12,90.1,283.06,454.98,注：,取,3.14159,各跑道的起跑线应该相差多少米？,7.85m,/7.86m,7.85,7.86,7.85,7.86,7.85,7.85,7.86,1,2,3,4,5,6,7,8,直径,(m),周长,(m),全长,(m),72.6,228.08,400,75.1,235.93,407.85,77.6,243.79,415.71,80.1,251.64,423.56,82.6,259.5,431.42,85.1,267.35,439.27,87.6,275.2,447.12,90.1,283.06,454.98,注：,取,3.14159,我不用算出每条跑道的长度，也知道它们相差多少米,?,两条直道是一样的，所以只需要看圆的周长。圆的周长是这样算的：,第一道：,72.6,第二道：,(72.6,2.5)=,72.6,2.5,第三道：,(75.1,2.5),=75.1,2.5,第四道：,(77.6,2.5),=77.6,2.5,第五道：,(80.1,2.5),=80.1,2.5,第六道：,(82.6,2.5),=82.6,2.5,第七道：,(85.1,2.5),=85.1,2.5,第八道：,(87.6,2.5),=87.6,2.5,每一条跑道都在上一条跑道的基础上增加,2.5,的长度。你能算出,2.5,是多少米吗？,终点,起点,200,米的跑道，每条道的长度都是它们全长的一半。,第一条：,4002=200,（,m,）,第二条：,407.852=203.925,（,m,）,第三条：,415.712=207.855,（,m,）,第四条：,423.562=211.78,（,m,）,第五条：,431.422=215.71,（,m,）,每条道相差,3.925m,或,3,39m,。所以起跑线应依次提前约,3.925m,。,思考：,200,米跑步比赛，跑道宽为,1.25,米，起跑线应依次提前多少米？,谢谢同学们,的坚持！,1,、老吾老以及人之老，幼吾幼以及人之幼。,20.7.147.14.202020:2620:26:02Jul-2020:26,2,、鞠躬尽瘁，死而后已。二二年七月十四日,2020,年,7,月,14,日星期二,3,、同是天涯沦落人，相逢何必曾相识。,20:267.14.202020:267.14.202020:2620:26:027.14.202020:267.14.2020,4,、人之相识，贵在相知，人之相知，贵在知心。,7.14.20207.14.202020:2620:2620:26:0220:26:02,5,、书到用时方恨少，事非经过不知难。,Tuesday,July 14,2020July 20Tuesday,July 14,20207/14/2020,6,、居安思危，思则有备，有备无患。,8,时,26,分,8,时,26,分,14-Jul-207.14.2020,7,、若要功夫深，铁杵磨成针。,20.7.1420.7.1420.7.14,。,2020,年,7,月,14,日星期二二二年七月十四日,8,、人无远虑，必有近忧。,20:2620:26:027.14.2020Tuesday,July 14,2020,亲爱的,读者,：,春去春又回，新桃换旧符。在那桃花盛开的地方，在这醉人芬芳的季节，愿你生活像春天一样阳光，心情像桃花一样美丽，感谢你的阅读。,1,、盛年不重来，一日难再晨。及时宜自勉，岁月不待人。,20.7.147.14.202020:2620:26:02Jul-2020:26,2,、千里之行，始于足下。,2020,年,7,月,14,日星期二,3,、少年易学老难成，一寸光阴不可轻。,20:267.14.202020:267.14.202020:2620:26:027.14.202020:267.14.2020,4,、敏而好学，不耻下问。,7.14.20207.14.202020:2620:2620:26:0220:26:02,5,、海内存知已，天涯若比邻。,Tuesday,July 14,2020July 20Tuesday,July 14,20207/14/2020,6,莫愁前路无知已，天下谁人不识君。,8,时,26,分,8,时,26,分,14-Jul-207.14.2020,7,、人生贵相知，何用金与钱。,20.7.1420.7.1420.7.14,。,2020,年,7,月,14,日星期二二二年七月十四日,8,、勇气通往天堂，怯懦通往地狱。,20:2620:26:027.14.2020Tuesday,July 14,2020,亲爱的,读者,：,春去春又回，新桃换旧符。在那桃花盛开的地方，在这醉人芬芳的季节，愿你生活像春天一样阳光，心情像桃花一样美丽，感谢你的阅读。,1,、生活不相信眼泪，眼泪并不代表软弱。,20.7.147.14.202020:2620:26:02Jul-2020:26,2,、世上没有绝望的处境，只有对处境绝望的人。二二年七月十四日,2020,年,7,月,14,日星期二,3,、成功都永远不会言弃，放弃者永远不会成功。,
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