练习册

  • 练习册
  • 试题
    26． 如图12.在直角梯形OABC中. OA∥CB.A.B两点的坐标分别为A.B.动点P.Q分别从O.B两点出发.点P以每秒2个单位的速度沿OA向终点A运动.点Q以每秒1个单位的速度沿BC向C运动.当点P停止运动时.点Q也同时停止运动．线段OB.PQ相交于点D.过点D作DE∥OA.交AB于点E.射线QE交轴于点F．设动点P.Q运动时间为t． (1)当t为何值时.四边形PABQ是等腰梯形.请写出推理过程, (2)当t=2秒时.求梯形OFBC的面积, (3)当t为何值时.△PQF是等腰三角形?请写出推理过程． 解:(1)如图4.过B作 则······ 过Q作 则 ························································································· 要使四边形PABQ是等腰梯形.则. 即 或(此时是平行四边形.不合题意.舍去)························· (2)当时.. ··············································· ···················································· ··································································· (3)①当时.则 ···························································································· ②当时. 即······················································ ③当时. ········· 综上.当时.△PQF是等腰三角形．·············· 【查看更多】

     

    题目列表(包括答案和解析)

    （09湖南怀化）先化简，再求值：其中

    查看答案和解析>>

    （09湖南怀化）先化简，再求值：其中

    查看答案和解析>>

    （09湖南怀化）若则         ．

    查看答案和解析>>

    2、09年春季，我国北方小麦产区遭到50年一遇旱灾，据山西省防汛抗旱指挥部副主任王林旺介绍，目前全省受旱面积达3274万亩，省财政紧急下拨抗旱资金1000万元，用于当前抗旱保吃水、保春浇、保春播工作．数据3274万亩用科学记数法表示为
    3.274×107
    亩．

    查看答案和解析>>

    2、据北京市交通管理局统计，截止09年4月1日，北京市机动车保有量已经超过360万辆，将3600000用科学记数法表示正确的是（　　）

    查看答案和解析>>


    同步练习册答案