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一个环形,它的面积是200cm^2,外沿大圆的半径是10cm.内沿小圆半径是多少?急但是不会解这个方程 设A为圆(x-2)^2+(y-2)^2=1上一动点,则A到直线x-y-5=0的最大距离是 设随机变量Y ~ N(10,22),求P{10 如果X是均值为10,方差为15的随机变量,那么P{5 双曲线|k|-2分之x²＋5-k分之y²=1那么k的取值范围是 双曲线x²/5+k+y²/9+k＝1求k的取值范围 圆x^2+y^2=25上一点P(-4,-3)的圆的切线方程是 圆O的方程为(x-3)^2+(y-4)^2=25,点(2,3)到圆上的最大距离为,最好手写!急圆O的方程为(x-3)^2+(y-4)^2=25,点(2,3)到圆上的最大距离为,最好手写 常温下,氢氧化钙的溶解度为0.148g,其溶于水达到饱和时存在如下关系,Ca(OH）2（g）=Ca（OH）2（aq）,Ca（OH）2（aq）=ca2+ + 2OH- ,若饱和石灰水的密度为1g/m³,则常温下Ca(OH)2的Ksp为? 修一段路,已修200米,还剩四分之一,这段路长几米? 数学题,求过程一杯糖水,糖占水的1/9,含糖率是（）.大米比面粉多20%,面粉比大米少（）.把甲的1/8拿给乙则甲乙相等.原来二数之比为（）,乙比 下列有关溶解度的选择题1、100克20摄氏度的硝酸钾饱和溶液蒸发掉10克水后,冷却到20摄氏度,这时（ ）A、溶液的浓度变大；B、溶液浓度变小C、溶液浓度不变；D、溶液变成了不饱和溶液2、固 高深几何体求助:已知一几何体的侧视图,俯视图,正视图分别如下图所示,求该几何体的体积, 食物在栖息地分配少,动物婚配制度是? 设B1,B2,B3是3维向量空间R^3的一组基,则由基B1,B2,B3到B1+B3,B1+B2,B2+B3的过度矩阵为麻烦带上过程 |B|=|(B1 B2 B3)|=1,B为三阶矩阵,det(2B1 B3 B2)= 已知一个面的法向量和面上一点面外一点如何求两点连线与平面所成角的正弦值? 怎么证明直角三角形的重心到斜边的距离等于斜边上的高的1/3 等腰直角三角形重心位置 一道关于溶液溶解度的化学题,急,在一定温度下,将某硝酸钾溶液200g,平均分成两份,其中一份蒸发掉60g水,析出硝酸钾晶体2.5g；另一份蒸发掉80g水,析出硝酸钾晶体7.5g,则在该温度下,硝酸钾的溶 B 做一篇小学英语阅读C tan(a+b)=1/2tan(a-b)=1/3.tan2a=______tan2b=_____详细过程, 如图,三角形ABC 角C=90°,BE⊥AB且BE=AB,且BD=BC,CB的延长线交DE于F,求证:点F是ED的中点 一篇高二英语阅读AAThe story is about two old people named David and Rosy Jackson.Both of them had very bad memories.For example,Rosy would forget to cook dinner or take vegetables home after paying for them.David would show up for work on Sun A recent report on online education,made by SRI International for the Department of Education,has a serious academic (学术的) title,but a most interesting conclusion:“ Students in online learning conditions performed better than those receiving 高二的一篇英语阅读Ever thought that you'd like another life?Is real life sometimes too real?Perhaps you would be better off with a second life.Well one of the biggest phenomena sweeping the Internet is something called exactly that---Second 一篇英语阅读,Most of us grew up taking family trips to the circus,zoo,marine park,and so on．Seeing animals caught for human amusement,seemed so natural that we never questioned it．While it is considered that all humans deserve freedom,we us 一篇高二英语阅读CC2.26-meter-tall Yao Ming made his NBA debut (初次登台) on October 23,2002 and got 6 points for the Houston Rockets in the game.The next day,he got 13 points (得分)in another game.Most people think that Yao Ming is a bo 已知sin(A+B)=3/5,sin(A-B)=1/5,证明：tan A=2tan B. 西格玛求和那个式子第二步m=0到n 为什么等于第三步m=1到n啊,没看懂.概率论 de是三角形abc的中位线,f是de的中点,bf的延长线交ac于点h,则ah：he等于《 三角形ABC中,角ABC等于100度,角C的平分线交AB边于点E,点D在AC边上,且满足角CBD等于20度,则角CED等于多少度?