三角函数

On two binomial coefficient s and their related combinatorial identities;2. Several identities on binomial coefficient s and trigonometric func tion values of special angles are obtained.

利用组合数学的一些技巧给出了切比雪夫多项式的通项表达式，并得到了一些二项式系数，特殊三角函数值的恒等

Double angle formula can transform the circular function equation to a biquadratic algebraic equation,and the analysis solution can be solved by extract equation directly.

用倍角公式可将该三角函数方程转化成一个四次代数方程，然后用求根公式直接求出解析解。

It showed that the inverse circular function equation had the best fitting to the process of yellow soil releasing cadmium at conditions with different acid rain. Besides, polynomial equations and two-constant equations can also describe this process properly.

结果表明，反三角函数方程对多种酸雨条件下黄壤吸附态镉释放过程的拟合度最佳，此外多项式方程、双常数方程也能较好地描述这一过程。

Use the image of cartesian coordinate system to solve trigonometic problems.

用直角坐标系的图像来解决有关三角函数的题目。

Vector mainly in plane geometry, Cartesian coordinate system, trigonometric functions, such as knowledge-based, learning through Vector, on the one hand, our mathematical expression of understanding entered a new field, on the other hand will enhance our space imagination capacity, the ability of thinking and analysis, the ability to solve practical problems.

向量主要以平面几何，直角坐标系，三角函数等知识为基础，通过向量的学习，一方面将我们对量的数学表达式的认识进入到一个新的领域，另一方面将增进我们的空间想象能力，思维能力和分析，解决实际问题的能力。

It used chebyshev polynomials to calculate sine function for improving its accuracy. It adopted optimized null vector distribution strategy to decrease switching times and switching current.

其采用Chebyshev多项式计算三角函数，提高了运算精度；采用零矢量象限间交错分布的优化策略，以减小开关次数，降低开关电流。

Some tedious calculations of circular functions and matrix were avoided by this algorithm.

使用该算法可避免出现三角函数、矩阵等复杂计算。

In the algorithm designs of hardware, it is difficult to realize the function that is both time-consuming and occupy area such as floating decimal circular functions, exponential function and logarithm function.

在硬件算法设计中，浮点三角函数、指数函数及对数函数等操作是既费时又占用面积的操作，很难有效实现。

So you want to show that a finite rank operator A on a Hilbert space is : compact?

三角函数全体在C上稠密，这个是如何证明的？

This article takes the teaching of conic sections as an example. By designing worksheets, teachers can introduce the historical material about conic sections to students. By way of using Apollonius' definition of parabola, ellipse and hyperbola, teachers can introduce the geometric aspect of "conic section" to students. By using the concept of " latus rectum " in Conics , we can connect "conic sections"-- representation of geometrical aspect, with "the equation of conic sections"-- representation of algebraic aspect to improving insufficiency of text books.

同时本文也试著从历史文本中寻找材料，简单举例说明数学教师可以如何应用这些史料在几何单元教学上，例如三角函数的正余弦定理，最后再以圆锥曲线的正焦弦为例，说明如何利用数学史料於此单元的教学，尤其是阿波罗尼斯的《锥线论》中对圆锥曲线的3个命题，将此3个命题的内容与意涵，尤其是正焦弦在圆锥曲线的几何意义上所扮演的角色，将其适当地融入教学中，将可使学生真正学习圆锥曲线的几何知识，而不再只是代数形式的几何知识。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。