求曲线r=asin

已知 在三角形ABC中D,E,F分别为边BC,CA,AB的中点,求证 四边形ABCD的周长等于AB+AC 在梯形ABCD中,BC‖AD,AB=DC,BC=2AD=4.BD⊥CD.CA⊥AB,E是BC的中点.判断三角形ADE的形状,求其周长 理论力学里点的运动一章包含的一道题目.点M作直线运动时具有加速度a=-kx,其中k为常量.已知当x=0时v=12m/s；又当x=3m时v=0.试求k值.高手回答闹,有积分赠送. 理论力学求动能的一道题目AB长为L,接触面光滑,A点瞬时速度V,求均质细杆AB的动能A、1/2mV^2 B、1/3mV^2 C、2/3mV^2 D、4/3mV^2 理论力学的一道题目,求约束力的大小 五年级下学期数学书p141-142答案 ··· 人教版的书p141-142的 新人教版五年级下册数学书142页有什么题? 设数列an是等差数列,a1 已知数列{an}是等差数列,且a1+a2=4,a7+a8=28,则S10=? Flashing back to the character as a young man...的结构Flashing back to the character as a young man helps the andience get used to Kutcher in the role结构是什么样的? 已知集合A={1,3,-x3},B={1,x+2},是否存在实数x,使B∪（CaB）=A?若存在,求集合A和B. 已知集合A=《1,3,-x2》,B=《1,x+2》,是否存在实数x,使得B∪（CaB）=A? A={1,3,-x的三次方},B={x+2,1}是应存在实数x,使B⊆A,若存在,求出集合A,B 把my father is warching TV in the room.改成否定句 在平行四边形中,BC=2AB,CA垂直于AB,求角B和角CAD的度数 What's the____of the word?(mean) you must walk into the room____.(quiet) 在平行四边形ABCD中,AB=3,BC=5,CA⊥AB,E为AB上的一定点,且AE=1,F为动点. 当F点在BC线段上时,BF=?△EBF为等腰三将形；当F在AD线段时,AF=?时,△BEF为等腰三角形 在平行四边形ABCD中,CA⊥AB,∠BAD=120°,BC=10cm ,则AC=____,平行四边形ABCD的周长是——. We must keep quiet and walk___out of the room A.We must keep quiet and walk___out of the room A.quiet B.quick C.quietly D.quite 在等差数列[an]中：d=负3分之1,a7=8 求a1 等差数列an中,d＝-3,a7＝10,则a1 星星为什么闪 6.I share a bedroom with my sister.My sister and I __________ in the __________ room. my （ ） sister is living with a student from sydney我妹妹和一个来自悉尼的学生住在一起 I went to the beach with my sister (对my sister提问) ( )7.I with my sister _______ TV.A.are watch B.are watching C.am watching D.is watching i ()one room with my sister.为什么用share peter walked into the room____because his father was sleeping .a.quietly b.quickiy c.carefullyd.kindly 2.Mrs.White e________ the room quietly,because her baby was sleeping.3.She kept on _______（举） her hand.4.He made some toys______________（please)his little son.5.They ___________ (talk)about the leture when I came in.6.His dog ___________(lie) 星星为什么闪 英语连词成句 blue.father.is.in.the.my.man急用 甲乙两辆汽车分别从ab两地相向开出,甲车每小时行42千米,乙车每小时行54千米.甲,乙两车第一次相遇后仍按原速继续前进,各自到达对方出发地点后立即按原路返回.两车从开出到第二次相遇共