[2013年高三数学第一轮复习讲义.ppt

Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 简单的三角 恒等变换 能运用上述公式进行简单的恒等变换(包括导出积化和差、和差化积、半角公式，但不要求记忆）. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 高考的必考内容,常利用其解决三角函数的化简、求值和三角恒等式的证明，也常同三角函数的值域、单调性结合在一起考查三角函数的综合应用. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 证明 化简 求值 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 【分析】用诱导公式及逆用两角和差的正、余弦公式，将70°,10°,40°化成与20°有关的角,约分求解. 考点1 三角函数式的化简 化简： Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 【解析】 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 【评析】三角函数式的化简要遵循“三看”原则. （1）一看“角”，这是最重要的一环，通过看角之间的差别与联系，把角进行合理的拆分，从而正确使用公式； （2）二看“函数名称”，看函数名称之间的差异，从而确定使用的公式，常见的有“切化弦”； （3）三看“结构特征”，分析结构特征，可以帮助我们找到变形的方向，常见的有“遇到公式要通分”等. 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. 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. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 考点2 三角函数式求值 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. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Pro