1、leadership intention and meaning into the text. Although his eyes now write only a relatively small number of materials, but also quite difficult, even to a molding material herself seems not very satisfied with the quality of service needs to be enhanced.Three is a lot of work to implement passive,
2、 active and advanced. Most contractors do matters assigned by the leadership, work is often in the orders, to implement the task, do not want to lead, not want to think ahead, plan ahead, and to seek the leadership; seek deep into the research, provide information good staff seek. Especially in the
3、writing process of material, it encountered much, time tight, heavy菱形的性质和判定类型1菱形与矩形1将矩形纸片ABCD按如图所示的方式折叠,得到菱形AECF.若AB3,则BC的长为( )A1 B2C. D.2(梧州中考)如图,在菱形ABCD中,B60,AB1,延长AD到点E,使DEAD,延长CD到点F,使DFCD,连接AC、CE、EF、AF,则下列描述正确的是( )A四边形ACEF是平行四边形,它的周长是4B四边形ACEF是矩形,它的周长是22C四边形ACEF是平行四边形,它的周长是4D四边形ACEF是矩形,它的周长是443如
4、图,已知矩形ABCD中(ADAB),EF经过对角线的交点O,且分别交AD,BC于E,F,请你添加一个条件:_,使四边形EBFD是菱形4.把两张宽为2 cm的矩形纸片重叠在一起,然后将其中的一张任意旋转一个角度,则重叠部分(图中的阴影部分)的四边形ABCD的形状为_,其面积的最小值为_cm2.5如图,菱形ABCD的对角线AC、BD交于点O,其中AC8,BD6,以OC、OB为边作矩形OBEC,矩形OBEC的对角线OE、BC交于点F,再以CF、FE为边作第一个菱形CFEG,菱形CFEG的对角线FG、CE交于点H,如此继续,第n个菱形的周长等于_6(朝阳中考)如图,O为矩形ABCD对角线的交点,DEA
5、C,CEBD.(1)求证:四边形OCED是菱形;(2)若AB3,BC4,求四边形OCED的面积7如图,在矩形ABCD中,M、N分别是AD、BC的中点,P、Q分别是BM、DN的中点(1)求证:PMPN;(2)四边形MPNQ是什么样的特殊四边形?请说明理由类型2菱形与几何作图8(丽水中考改编)如图,小红在作线段AB的垂直平分线时,是这样操作的:分别以点A,B为圆心,大于线段AB长度的一半的长为半径画弧,相交于点C,D,则直线CD即为所求连接AC,BC,AD,BD,根据她的作图方法可知四边形ADBC一定是( )A矩形 B菱形C平行四边形 D以上都不对9如图,在ABC中,ABBCAC,小华依下列方法作
6、图,作C的角平分线交AB于点D;作CD的中垂线,分别交AC,BC于点E,F;连接DE,DF.根据小华所作的图,下列说法中一定正确的是( )A四边形CEDF为菱形 BDEDACDFCB DCDBD10如图,在ABCD中,用直尺和圆规作BAD的平分线AG交BC于点E,以A为圆心,AB为半径的弧交AD于点F,连接EF.若BF6,AB5,则四边形ABEF面积是( )A48 B36 C24 D1211如图,在MON的两边上分别截取OA、OB,使OAOB;分别以点A、B为圆心,OA长为半径作弧,两弧交于点C;连接AC、BC、AB、OC.若AB2 cm,四边形OACB的面积为4 cm2.则OC的长为_cm.
7、12如图,在RtABC中,ACB90,AC4,BC3,D为斜边AB上一点,以线段CD,CB为边作CDEB,当AD_时,CDEB为菱形13(济宁中考)如图,在ABC中,ABAC,DAC是ABC的一个外角实验与操作:根据要求进行尺规作图,并在图中标明相应字母(保留作图痕迹,不写作法)(1)作DAC的平分线AM;(2)作线段AC的垂直平分线,与AM交于点F,与BC边交于点E,连接AE,CF.猜想并证明:判断四边形AECF的形状,并加以证明14(邵阳中考)已知在RtABC中,ACB90,现按如下步骤作图:分别以A,C为圆心,a为半径(aAC)作弧,两弧分别交于M,N两点;过M,N两点作直线MN交AB于
8、点D,交AC于点E;将ADE绕点E顺时针旋转180,设点D的像为点F.(1)请在图中直接标出点F并连接CF;(2)求证:四边形BCFD是平行四边形;(3)当B为多少度时,四边形BCFD是菱形?参考答案1D2.B3.EFBD4.菱形45.6.(1)证明:DEAC,CEBD,四边形OCED为平行四边形四边形ABCD为矩形,ODOC.四边形OCED为菱形(2)四边形ABCD为矩形,BODOBD,SOCDSOCBSABC.SOCDSOCBSABC343.S菱形OCED2SOCD6.7.(1)证明:连接MN.四边形ABCD是矩形,BAD90,ADBC,ADBC.M、N分别是AD、BC的中点,AMDMAD
9、,BNCNBC.AMBNMDCN.四边形AMNB是平行四边形又A90,四边形AMNB是矩形MNB90.P是BM的中点,PNBMPM.(2)四边形MPNQ是菱形理由如下:DMBN,DMBN,四边形BMDN是平行四边形BMND,BMND.又P、Q分别是BM、DN的中点,PMNQ.四边形MPNQ是平行四边形PMPN,四边形MPNQ是菱形8.B9.A10.C11.412.13.实验与操作:如图所示猜想并证明:四边形AECF的形状为菱形理由如下:设EF交AC于点O.ABAC,ABCACB.AM平分DAC.DAMCAM.而DACABCACB,CAMACB.EF垂直平分AC,OAOC,AOFCOE.在AOF
10、和COE中,AOFCOE.OFOE.即AC和EF互相垂直平分,四边形AECF为菱形14.(1)图略(2)根据作图可知:MN垂直平分线段AC,ACB90,D、E为线段AB和AC的中点DE是ABC的中位线DEBC.将ADE绕点E顺时针旋转180,点D的像为点F,EFED.DFBC.DEBC,四边形BCFD是平行四边形(3)当B60时,四边形BCFD是菱形B60,ACB90,A30.BCAB.DBAB,DBCB.四边形BCFD是平行四边形,四边形BCFD是菱形between the requirements. And in the encounter the tedious work, comple
11、x things, sometimes take the method of escape, that bridge the boat to the bridge straight , not their own force please find countermeasures, but to wait for the self, the lack of a spirit of hard research.Two, the cause of the problemThrough the analysis, I feel that there are many reasons for these problems.One idea is obsolete. The failure to do system research on the essence of reading the original, palm and master the theory of quality read without thorough understanding, has not been effectively7