六年级上册《确定起跑线》课件.ppt

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1、确定起跑线人教版数学六年级（上）132终点线85.96m72.6m1.25m1.25m1.25m85.96m72.6m1.25m1.25m1.25m注：π取3.1415985.96m72.6m第一道直径：周长：全长：72.6m72.6×3.14159≈228.08（m）85.96×2＋228.08=400（m）72.6228.08400注：π取3.1415985.96m72.6m第一道直径：周长：全长：72.6m228.08m400m第二道直径：周长：全长：72.6＋1.25＋1.25=75.1（m）75.1×3.1415

2、9≈235.93（m）85.96×2＋235.93=407.85（m）1.25m1.25m72.6228.0840075.1235.93407.85注：π取3.1415985.96m72.6m第二道直径：周长：全长：75.1m235.93m407.85m第三道直径：周长：全长：75.1＋1.25＋1.25=77.6（m）77.6×3.14159≈243.79（m）85.96×2＋243.79=415.71（m）1.25m1.25m75.1m72.6228.0840075.1235.93407.8577.6243.79415

3、.71注：π取3.1415985.96m72.6m第三道直径：周长：全长：77.6m243.79m415.71m第四道直径：周长：全长：77.6＋1.25＋1.25=80.1（m）80.1×3.14159≈251.64（m）85.96×2＋251.64=423.56（m）1.25m1.25m77.6m72.6228.0840075.1235.93407.8577.6243.79415.7180.1251.64423.56注：π取3.1415985.96m72.6m第四道直径：周长：全长：80.1m251.64m423.56

4、m第五道直径：周长：全长：80.1＋1.25＋1.25=82.6（m）82.6×3.14159≈259.50（m）85.96×2＋259.5=431.42（m）72.6228.0840075.1235.93407.8577.6243.79415.7180.1251.64423.5682.6259.5431.42注：π取3.1415985.96m72.6m第五道直径：周长：全长：82.6m259.5m431.42m第六道直径：周长：全长：82.6＋1.25＋1.25=85.1（m）85.1×3.14159≈267.35（m）

5、85.96×2＋267.35=439.27（m）72.6228.0840075.1235.93407.8577.6243.79415.7180.1251.64423.5682.6259.5431.4285.1267.35439.27注：π取3.1415985.96m72.6m第六道直径：周长：全长：85.1m267.35m439.27m第七道直径：周长：全长：85.1＋1.25＋1.25=87.6（m）87.6×3.14159≈275.20（m）85.96×2＋275.2=447.12（m）72.6228.0840075.

6、1235.93407.8577.6243.79415.7180.1251.64423.5682.6259.5431.4285.1267.35439.2787.6275.2447.12注：π取3.1415985.96m72.6m第七道直径：周长：全长：87.6m275.2m447.12m第八道直径：周长：全长：87.6＋1.25＋1.25=90.1（m）90.1×3.14159≈283.06（m）85.96×2＋283.06=454.98（m）72.6228.0840075.1235.93407.8577.6243.7941

7、5.7180.1251.64423.5682.6259.5431.4285.1267.35439.2787.6275.2447.1290.1283.06454.98注：π取3.14159各跑道的起跑线应该相差多少米？7.85m/7.86m7.857.867.857.867.857.857.8672.6228.0840075.1235.93407.8577.6243.79415.7180.1251.64423.5682.6259.5431.4285.1267.35439.2787.6275.2447.1290.1283.06

8、454.98注：π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×π第二道：(72.6＋2.5)×π=72.6π＋2.5π第三道：(75.1＋2.5)×π=75.1π＋2.5π第四道：(77.6＋2.5)×π=