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2、△ABC中,AB的垂直平分线交AC于D,如果AC=5 cm,BC=4cm那么△DBC的周长是（ ）（A）6cm （B）7cm （C）8cm （D）9cm 1.已知AB=AE BC=ED ∠B=∠E 求证：点A在DC的垂直平分线上（是一个五边形来的）2.已知在△ABC中 ∠A=30度 ∠C=90度 BD是∠ABC的角平分线 交AC于点D 求证 点D在AB的垂直平分线上3.已知△ABC中 ∠C=90度 已知:u=R,A={x/-4≤x≤2}B={x/-1 已知集合U=R,A={x/-1 ∫x f'(2x+1)dx f(x)=x^0.5+1,则∫_(0,1)f(2x)dx=?我的想法是f(2x)=(2x)^0.5+1,然后求出结果.我算出来是2*(2)^0.5÷3+1,但答案是2^0.5÷2. 已知a=0.00···049(2014个0)49,b=0.00···07(2014个0),那么a÷b=_____. a等于0.002014个049,等于0.00.07（2014个零)那么a除以B是等于多少 函数y=根号3*2^(x+1)-8-4^x的定义域是 值域是 一只船顺流航行速度为A千米/小时 逆流航行速度为B千米/小时 （A＞B＞0） 说明这样写的原因,越详细越好, 3道数学问题 要算式 回答好的立即采纳1.一根铁丝,剪去6m,剩下的比全长的百分之60短1m,还剩下多少米?2.有含盐率是百分之20的盐水80克,如果再倒入4克盐,制成一种新的盐水.求这种新的盐水的含 3道数学（要算式和解答）（1）用长8厘米,宽12厘米的长方形纸拼成一个正方形,拼成的正方形的边长最小是多少厘米?（2）一满瓶的油连瓶重650克,用去一半后连瓶重400克,瓶重多少克?油重多少 1.一只船顺流航行的速度为A千米/时.逆流航行的速度为B千米/时(A>B> 0),则水流速度为多少千米每时? One of the most scenic areas is the Loire Valley,where you can visit the old castles in which the kings and queens of France used to live.这句话里面为什么有in?in在这里表达的是什么意思? Loire Valley is the most scenic area in the France改为同义句 英语翻译原句:After Yellowstone became a public park,"many other areas of great scenic importance were set aside "--- and in 1916 the National Park Service was established to manage these parks注意!要翻译的那句中的主语绝对不是imp y=(1/2)^1/x 求定义域和值域 一艘客轮往返于A、B两地,从A到B顺流需要m小时,若水流的速度为a,求逆流从B到A所需要的时间.如果有会做的, 设点M（a,b）在不等式组x-y+6>=0,x+y>=0,x 一艘客船从A地到B地,顺流用了4小时,从B地到A地,逆流用了35小时,已知水流速度是3K/M,求船静水的速度. AB两地顺流要m小时,水流速度为a,问逆流要多少时间 英语翻译Most of the criminals attempt by a form of reasoning,fallacious or logical,to justify their antisocial acts even to themselves,consequently stoutly maintaining that they should never have been imprisoned at all.书中的翻译是,多数 where were you on和when were you at的回答句式 Where were you when I ____?I was ____ on the playground.Where were you when I ____?I was ____ on the playground.A arrived at; at play B reached; at play C got; playing D arrived in ; playing there is no way around是什么意思呀~~ 两个分数的分母的公因数只有1,它们的和是33分之11,这两个分数是( )和( ) a分之b和c分之d(ABCD都不为0)两个分数的分母只有公因数1,他们的最小公分母是 “已定义”的英语怎么写?百度翻译我也会,有不有人知道呢? all 和 all of区别 再搭配代词时 如all of which which all 微积分计算题 设y=e^x/1+5^x,求dy 设y=e1/x次方+5x次方 求dy 设y=x的5x次方,求dy