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Transform the difference of two squares into a rectangle, the ratio of two sides being 2 : 3.
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With BC, one leg of △ABC, as diameter, a circle is described intersecting the hypotenuse AC at P. From P draw a tangent intersecting AB at D. Showt hat AD = BD.
Show that the line joining the mid-points of the diagonals of a trapezoid is half the difference of its bases.
Evaluate to four significant figure by logarithm,
Simplify yz(x+a)/(x-y)(x-z)+zx(y+a)/(y-z)(y-x)+xy(z+a)/(z-x)(z-y)
Determine the real value of k, so that the roots of equation, (k - 1)x² - kx - 2x + 4 = 0, may be real and equal.
Solve and verify x²+3x-6(x²+3x-3)1/2+2=0
圣约翰大学幂函数
There are two groups of boys on the street corner. One boy leaves the first group and joins the second. The groups are then equal in size. If one boy had left the second group and joined the first, the first group would then have been three times as large as the second. Find the original size of each group.
Determine the graph of y = x² + x + 1. Find the coordinates of its vertex and the equation of its axis.
求(x³+1/x² )20中之x45之系数.
如图,已知正方形ABCD的边CD上任意一点E.延长BC到F,使CF=CD.设BE与DF相交于G,求证:BG⊥DF.
已知ABCD,A'B'C'D'都是正方形(如图),而A'、B'、C'、D'分别把AB、BC、CD、DA分为m:n,设AB=1.(1)求A'B'C'D'的面积;(2)求证A'B'C'D'的面积不小于1/2.
联四边对边中点之两直线,必互为二等分,试证之.
于四边形之内,取一点不在两对角线之交点之上者,试证明从此点至各顶点之距离之和大于两对角线之和.
ABCD is a rectangle. and a straight line APQ cuts BC in P & DC extended in Q. Locate the point P so that the sum of the areas of the two triangles ABP&CPO may be a minimum.
PQRS为平面四边形,QR=1,∠PQR= ∠QRS= 70°,∠PQS=15°,∠PRS= 40°.若∠RPS=θ.PQ=α,PS=β,则4αβsinθ属于下列哪个区间【 】
试作一正方形,与一已知长方形之面积相等.
求作一四角形,与一已知四角形等角而外切于一定圆.
设ABCD为一平行四边形,AC为对角线,由B作任意直线各交AC、CD及AD于F、G及E,求证EF·FG=BF².
设有一三角形,其底为 7 cm,高为 5 cm,用圆规及尺作一正方形,其面积与此相等者.
There are 4n pebbles of weights 1,2,3,…,4n. Each pebble is coloured in one of n colours and there are four pebbles of each colour. Show that we can arrange the pebbles into two piles so that the following two conditions are both satisfied:● The total weights of both piles are the same.● Each pile contains two pebbles of each colour.有 4n 枚石子,重量分别为 1 , 2 , 3 , … , 4n .每一枚小石子都染了n种颜色之一,使得每种颜色的小石子恰有四枚.证明:可以把这些小石子分成两堆,且满足以下两个条件:● 两堆小石子的总重量相同;● 每堆中每种颜色的小石子各有两枚.(匈牙利供题)
如图,小圆圈表示网络的结点,结点之间的连线表示它们有网线相连.连线标注的数字表示该段网线单位时间内可以通过的最大信息量.现从结点A向结点B传递信息,信息可以分开沿不同的路线同时传递,则单位时间内传递的最大信息量为【 】
如图,AB是⊙O的直径,CB是⊙O的切线,切点为B,OC平行于弦AD.求证:DC是⊙O的切线.
已知:如图,MN为圆的直径,P、C为圆上两点,连PM、PN,过C作MN的垂线与MN、MP和NP的延长线依次相交于A、B、D,求证:AC2=AB·AD.
有一个圆内接三角形ABC,∠A的平分线交BC于D,交外接圆于E,求证:AD·AE=AC·AB.
如图所示,O是△ABC的内心,∠BOC=100°,则∠BAC=______度.
沈括的《梦溪笔谈》是中国古代科技史上的杰作,其中收录了计算圆弧长度的“会圆术”.如图,(AB) ̂是以O为圆心,OA为半径的圆弧,C是AB的中点,D在(AB) ̂上,CD⊥AB.“会圆术”给出(AB) ̂的弧长的近似值s的计算公式:s=AB+CD2/OA.当OA=2,∠AOB=60°时,s=【 】
过四点(0,0),(4,0),(-1,1),(4,2)中的三点的一个圆的方程为____________.
如图,AD=BC=6,AB=20,∠ABC=∠DAB=120°,O为AB中点,曲线CMD上所有的点到O的距离相等,MO⊥AB,P为曲线CM上的一动点,点Q与点P关于OM对称.(1)若P在点C的位置,求∠POB的大小; (2)求五边形MQABP面积的最大值.
Suppose a convex pentagon ABCDE such that BC=DE.If there exists a point T inside ABCDE suchthat TB=TD TC=TE and ∠ABT=∠TEA. AB meet CD and CT at point P and Q respectively, withP,B,A,Q in this order on the same line. AE meet CD and DT at point R and S respectively, with R,E,A,S in this order on the same line.Prove that P,S,Q,R are on the same circle.译文:设凸五边形ABCDE满足BC=DE.若在ABCDE内存在一点T使得TB=TD,TC=TE且∠ABT= ∠TEA.直线AB分别与直线CD和CT交于点P和Q,且P,B,A,Q在同一直线上按此顺序排列;直线AE分别与直线CD和DT交于点R和S,且R,E,A,S在同一直线上按此顺序排列.证明:P,S,Q,R 四点共圆.