The triangle , made up of a bar of round steel bent into the shape of an equilateral triangle with one corner open , is struck with a short metal rod 三角铃是用一根铁条，弯成等边三角形，而其中一角并没有衔接。演奏时，用一条绳把它吊起，拿一根小铁棒敲响。
A kaleidoscope creates stunning visual effects by reflecting the edges of the mirrors and the space enclosed between them repeatedly . mirrors arranged in an equilateral triangle , a square or a regular hexagon behave in a similar manner 万花筒将旁边的三角形平面及相关的空间利用镜子不断重覆，有此功能的镜子组合包括三角形正方形和正六边形等。
The current trends of this field is to acquire the current density of dipole distribution rather than a few dipoles . based upon that , a new model was proposed - dipole layer localization method ( dllm ) : spherical dipole layer was used as source model , on which dipoles were distributed by equilateral triangles ; three concentric inhomogeneous sphere was used as head model , which contains scalp , skull and cortex with different conductance . the dipole distribution and scalp potential tomography were obtained with singular value decomposition ( svd ) 鉴于该领域的研究趋势已从求取少数偶极子过渡到偶极子分布密度的获得，本文提出了新的模型? ?偶极面定位方法( dipolelayerlocalizationmethod ， dllm ) ：以等边三角形均匀分布的偶极子构成的偶极面(球面)作为源模型；包括头皮、颅骨和皮层的三层同心介质球作为头颅模型，运用奇异值分解来求解逆问题，从而获得偶极子分布和头皮电位分布，实现三维成像。
They often solve the problems with two methods . the first one is disturbing and controlling the spurting water with a movable baffle - plate . the second is the proper arrangement of the sprinklers , ( such as isoceles triangle distribution , equilateral triangle distribution , square distribution , and rectangle distribution ) 喷灌的均匀度不高的问题由来已久，国内外的喷灌技术研究人员为解决该问题一般从“干扰、控制从喷嘴喷出的水舌” (利用挡水板和导流板来实现)与“合理的安排喷头的组合形式” (等腰三角形布置、等边三角形布置、正方形布置、长方形布置)上来。
Janos pach and rom pinchasi ( see [ 61 ] ) proved that any set of n points in strictly convex position in the plane has at most [ 2 ( n - 1 ) / 3j triples that induce unit triangles ( equilateral triangles of side length one ) , and any set of n points in convex position in the plane has at most n - 2 triples that induce unit triangles 平面中任一处于凸位abstract置的二一点集至多有2 。一4个三元组满足:每一三元组均导出一个与t0全等的三角形.定理2 . 2 .给定一等腰直角三角形t0 ，平面中任一处于强凸位置的n一点集至多有二个三元组满足:每一三元组均导出一个与几全等的三煮形
Fluid noise mainly comes from out put pulsation of rate of flow , the main reason of out put pulsation of rate of flow is the instant high pressure return flow that obturation cubage produced when the big round curve pressure transition . the v trough on the port plate can reduce the fluid noise . in this paper , the author based on the acting of dam a river and condensability of liquid and used matlab language as tool to calculate the v trough on the original port plate and drew out the p - t diagrammatic curve and analyzed its shortcoming and improved the design of original v trough and got that the best size of its angle was 12 . 3 and its length was 5mm and the cross section was an equilateral triangle 流体噪声主要来源于输出流量脉动，造成输出流量脉动的主要原因是闭死容积在大圆弧段压力切换时产生的瞬时高压回流，在配流盘上开设v型尖槽可降低因高压回流而引起的流体噪声，本文以截流作用和液体的可压缩性为理论依据，以matlab语言为工具，对原配流盘上的v型尖槽进行了理论计算，绘制出p - t图线，分析了它的不足，并对原有v型尖槽进行了优化设计，得出了v型尖槽的最佳几何尺寸：配流盘平面上的v型尖槽的两边的夹角为12 . 3 ，槽长5mm ，槽的横截面为等边三角形。
There are 2 methods in dividing the surfaces : alternate division class i and triacon division class ii . alternate division is to divide the equilateral triangle into n2 smaller equilateral triangles by breaking each edges into n pieces and connecting the breaking points with lines parallel to the triangle edges 分解方法有两种交错分解法i类以及三十面分解法ii类，交错分解法是将正多面体上的正三角形面每边切成n份并把分解点连成和大正三角形的边平行的直线，使正三角形面分解成n2个较小的正三角形面。
Firstly a microstrip - fed microstrip patch antenna has been emulated and validated . on the base of this , the multi - band property of sierpinski equilateral triangle and squareness microstrip fractal patch antennas are carefully studied , and the effect of antenna ' s property by the permittivity , the size of patch , the order of the fractal and the decrease of fractal patches is depicted ; secondly on the base of analysis and comparison of performance of microstrip - fed semicircle and rectangle double - band microstrip patch antennas , warranty of dimension curtailment is offered ; finally expansion of band of those antennas above is discussed 在此基础上，着重分析了微带线耦合馈电的sierpinski等边三角形微带分形贴片天线以及sierpinski方形微带分形贴片天线的多频特性，给出了介质参数、贴片尺寸、分形的阶数以及减少分形贴片数对微带线耦合馈电的sierpinki等边三角和sierpinski方形微带分形贴片天线特性的影响；其次基于微带线耦合馈电的半圆双频微带贴片天线和矩形双频微带贴片天线的性能分析和比较，提供了尺寸缩减的依据；最后对以上天线的频带扩展进行了探论。
