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已知圆O:x^2+y^2=r^2,点P(x0,y0).
1.当点P在圆t时,我们知道x0x+y0y=r^2。为过点P(x0,y0)的圆O的切线方程. 相似文献
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已知定点P1(x1,y1),P2(x2,y2)在直线l:Ax+By+C=0外,直线l与直线P1P2相交于点P,若P1P→=λPP2→,则称λ为直线l分P1P2→所成的比.当P在线段P1P2上时,λ=〉0,当P在线段P1P2的延长线上时,λ〈-1,当P在线段P1P2的反向延长线上时,-1〈λ〈0. 相似文献
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若P→q,则q是P的必要条件;若P→←q,则P是q的充要条件。解题时,同学们常常挖掘必要条件来作为解题的突破口,但应特别注意不要以“必要条件”充当“充要条件”,否则会出现解题错误.下面略举数例说明之,供同学们参考. 相似文献
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将塞瓦定理推广到三维空间得到结论:P是不在四面体的面所在平面上的一点.且P点不在过棱且平行于对棱的平面上,则四面体的各棱中点,过各棱与点P的平面与对棱所在直线的交点,及过各顶点与点P的直线与四面体对面所在平面的交点和四面体在这个面上的顶点的连线中点.这24个点在同一个二次曲面上.当点P在四面体内或四面体的三面角的对顶角区域内时,24点二次曲面为椭圆面;当点P在四面体的面分空间所成的其它区域内时,24点二次曲面为双曲面或二阶锥面. 相似文献
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降维法是指将三维立体几何问题化归到 二维平面问题.本文将一类空间轨迹回归求平 面曲线轨迹. 例1 (2004重庆市高考题)在四面体 ABCD的面ABC内有一点P,P到平面BCD 的距离等于P到AB的距离,则在平面ABC 内的P点轨迹为( ). 相似文献
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非自伴椭圆问题的离散强极值原理与区域分解法 总被引:1,自引:0,他引:1
1.引言本文考虑非自伴二阶椭圆型方程的边值问题():其中Q是有界多角形开域,其边界*O充分光滑;并且方程左端微分算子是H’川椭圆的.虽然在一定条件下问题(P)的解满足极值原理,但是,用通常的Galerkin有限元法求解(P)时,得到的解叫的一般并不满足极值原理.特别,当问>>a时,qx)还可能出现剧烈的振荡.即使对自伴问题(即(卫.1)中b一时在三角形线性元的情形,P.G.O。小t和P.-A.Ravlart证明了:如果限定三角形的内角。三。/2-。(其中常数。>则,且网格参数人>0充分小时,则有较弱形式的极值原理:maxfrU(… 相似文献
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本文推广了R.W.Thatcher[4]的结果,给出局部质量守恒的P3-P2元,并对矩形网格的高阶Qn-Qn-1进行了讨论. 相似文献
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《数学学报(英文版)》2014,(10)
<正>Submission Authors must use LaTeX for typewriting,and visit our website www.actamath.com to submit your paper.Our address is Editorial Office of Acta Mathematica Sinica,Academy of Mathematics and Systems Science,Chinese Academy of Sciences,Beijing 100190,P.R.China. 相似文献
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《运筹学学报》2014,(3)
正August 10-14,2015Beijin,China The International Congress on Industrial and Applied Mathematics(ICIAM)is the premier international congress in the field of applied mathematics held every four years under the auspices of the International Council for Industrial and Applied Mathematics.From August 10 to 14,2015,mathematicians,scientists 相似文献
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ZhouSongping YaoKui SuWeiyi 《分析论及其应用》2004,20(4):332-341
The present paper investigates the fractal structure of fractional integrals of Weierstrass functions. The ezact box dimension for such functions many important cases is established. We need to point out that, although the result itself achieved in the present paper is interesting, the new technique and method should be emphasized. These novel ideas might be useful to establish the box dimension or Hausdorff dimension (especially for the lower bounds) for more general groups of functions. 相似文献
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《应用数学学报(英文版)》2014,(4)
正1 Aims and Scope Acta Mathematicae Applicatae Sinica(English Series)is a quarterly journal established by the Chinese Mathematical Society.The journal publishes high quality research papers from all branches of applied mathematics,particularly welcomes those from partial differential equations,computational mathematics,applied probability,mathematical finance,statistics,dynamical systems,optimization and management science. 相似文献
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We characterize congruence lattices of standard QBCC-algebras and their connection with the congruence lattices of congruence
kernels.
Work on the paper was supported by Council of Czech Government No J14/98:153100011. 相似文献
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A new class of sets in ideal topological spaces is introduced and using these sets, a decomposition of continuity is given.
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We obtain (a) necessary and sufficient conditions and (b) sufficient conditions for a compact (countably compact) set to be closed in products (sequential products) and subspaces (sequential subspaces) of normal spaces. As a consequence of these, sufficient conditions are obtained for (i) the closedness of arbitrary (countable) union of closed sets and (ii) the equality of the union of the closures and the closure of the union of arbitrary (countable) families of sets in these spaces. It is also shown that these results do not hold for quotients of even T
4,-spaces. 相似文献