切线的长

By means of uniting geometry with algebra, the arc length, tangent line, cotangent space and curvature of curve in four dimensional space are investigated, and the corresponding calculation formula in each cases are given.

用形数结合的观点研究了四维空间中曲线的弧长、切线、法空间和曲率问题，并给出了其计算公式。

The critical aspect ratio of the fiber is defined as the crosspoint of the tangent value of the inflexion and the asymptote of the maximum elastic modulus.

将与曲线拐点切线和最大值水平直线交点相对应的长径比值定义为纤维临界长径比，将与此相对应的函数值定义为弹性模量临界值。

There are two tangent lines from a point outside the circle, the two tangent lengths are equal.

从圆外一点可以引圆的两条切线，它们的切线长相等。

150HP-300HP screw air compressor rotor is the German GHH-RAND joint shaft type unit,adopts the third generation asymmetrical dentate 5:6 rotors,The major axis is more reasonable than the choice, the tangent speed of rotors is only 30-36m/s, is far lower than that———60m/s of common air compressors, it keeps 0.003INCH between rotors that will not abrase forever, the space between teeth dropping variance is small, so the backflow loses is slight, Enhances10-12% kf the efficiency compared to the 4:6 dentate, save power 20%, adopts the Swden SKF bearing.

150HP-300HP）螺杆机转子为德国GHH-RAND联轴式机组，采用第三代非对称齿型为5：6的转子，长径比选择合理，其转子的切线速度仅为30'36m/s，远低于一般空压机60m/s 的切线速度，转子之间保持0.003INCH间隙永不磨损，齿间落差小，故回流损失小，比4：6齿型提高效率10-12%，省电20%，采用瑞典SKF轴承，极大延长了主机的寿命。

Br/br/Adopts the GHH-RAND remarkable mainfrane br/(150HP-300HP) screw air compressor rotor is the German GHH-RAND joint shaft type unit,adopts the third generation asymmetrical dentate 5:6 rotors,The major axis is more reasonable than the choice, the tangent speed of rotors is only 30-36m/s, is far lower than that60m/s of common air compressors, it keeps 0.003INCH between rotors that will not abrase forever, the space between teeth dropping variance is small, so the backflow loses is slight, Enhances10-12 kf the efficiency compared to the 4:6 dentate, save power 20, adopts the Swden SKF bearing.

采用GHH-RAND卓越主机br/（150HP-300HP）螺杆机转子为德国GHH-RAND联轴式机组，采用第三代非对称齿型为5：6的转子，长径比选择合理，其转子的切线速度仅为3036m/s，远低于一般空压机60m/s 的切线速度，转子之间保持0.003INCH间隙永不磨损，齿间落差小，故回流损失小，比4：6齿型提高效率10-12，省电20，采用瑞典SKF轴承，极大延长了主机的寿命。

Theory; the spatial meshing theory includes comparative motion, comparative differential and conjugative curved surface; and the application of meshing theory includes gear drive and worm drive. The spatial meshing theory is the main part of the course.

课程的重点讲解内容有曲线的参数方程、切线、法面、弧长、曲率、空间曲线的基本公式、挠率及平面曲线的基本公式等；曲面第一和第二基本公式，法曲率、主方向和主曲率、欧拉公式、短程挠率、欧拉公式和贝特朗公式推广、相对法曲率和相对短程挠率等；刚体的绝对和相对运动速度、相对微分和绝对微分、相对速度和相对微分、轨迹曲面的法曲率和短程挠率等；空间共轭曲面的啮合条件、诱导法曲率、两类界限点、等距共轭曲面、空间啮合的二次接触原理等；蜗杆传动的数学模型建立及啮合特性分析方法等。

Singer Leona Lewis and former Led Zeppelin guitarist Jimmy Page emerged as the bus transformed into a grass-covered carnival float, and the pair combined for a rendition of "Whole Lotta Love".

歌手leona刘易斯和前率领的飞艇的吉他手吉米页出现巴士转化为基层所涵盖的嘉年华花车，和一双合并为一移交&整个lotta爱&。

This is Kate, and that's Erin.

这是凯特，那个是爱朗。