[直棱柱和圆锥的侧面展开图.ppt

Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. A C B C”（C） C’（C） 4cm 如图，有一边长4米立方体形的房间，一只蜘蛛在A处，一只苍蝇在B处。⑴试问，蜘蛛去抓苍蝇需要爬行的最短路程是多少？ ⑵若苍蝇在C处，则最短路程是多少？ 4cm Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. A B C 6cm 4cm 如果换成长方体纸盒又会怎么样呢？ 4cm C ′′ C′ E F D G′ H G E ′ Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 观察下图中的立体图形，它们的形状有什么共同特点？ 观察 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 在几何中，我们把上述这样的立体图形称为直棱柱，其中“棱”是指两个面的公共边，它具有以下特征： （1） 有两个面互相平行，称它们为底面； （2）其余各个面均为矩形，称它们为侧面； （3）侧棱（指两个侧面的公共边）垂直于底面. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 根据底面图形的边数，我们分别称图中的立体 图形为直三棱柱、直四棱柱、直五棱柱、直六棱柱. 例如，长方体和正方体都是直四棱柱.底面是正多边 形的棱柱叫作正棱柱. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 甲 展开 展开 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 展开 五棱柱 展开 六棱柱 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 一个食品包装盒的侧面展开图如图所示，它的 底面是边长为2的正六边形，这个包装盒是什么 形状的几何体？试根据已知数据求出它的侧面积. 举 例 例1 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 解 根据图示可知该包装盒的侧面是矩形，又已知上、下底面是正六边形，因此这个几何体是正六棱柱（如图所示）. 由已知数据可知它的底面周长为2×6=12， 因此它的侧面积为12×6=72. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 如图，上面的图形分别是下面哪个立体图形展开的形状？把它们用线连起来。 连一连： Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0