练习册

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    24． 解:(1)设抛物线的解析式为．······················································· 1分 将代入上式.得． 解.得．············································································································ 2分 抛物线的解析式为． 即．··································································································· 3分 (2)连接.交直线于点． 点与点关于直线 对称. ．······························································ 4分 ． 由“两点之间.线段最短 的原理可知: 此时最小.点的位置即为所求．················ 5分 设直线的解析式为. 由直线过点..得 解这个方程组.得 直线的解析式为．············································································· 6分 由(1)知:对称轴为.即． 将代入.得． 点的坐标为(1.2)．···························································································· 7分 说明:用相似三角形或三角函数求点的坐标也可.答案正确给2分． (3)①连接．设直线与轴的交点记为点． 由(1)知:当最小时.点的坐标为(1.2)． ． ．·························································································· 8分 ． ． 与相切．······································································································ 9分 ②．················································································································· 11分 【查看更多】

     

    题目列表(包括答案和解析)

    （本题满分11分）某公园有一个抛物线形状的观景拱桥ABC，其横截面如图所示，在图中建立的直角坐标系中，抛物线的解析式为且过顶点C（0，5）（长度单位：m）

    【小题1】（1）直接写出c的值；
    【小题2】（2）现因搞庆典活动，计划沿拱桥的台阶表面铺设一条宽度为1．5 m的地毯，地毯的价格为20元／m2，求购买地毯需多少元?
    【小题3】（3）在拱桥加固维修时，搭建的“脚手架”为矩形EFGH（H、G分别在抛物线的左右测上），并铺设斜面EG．已知矩形EFGH的周长为27．5m，求点G的坐标．

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    （本题满分11分）某公园有一个抛物线形状的观景拱桥ABC，其横截面如图所示，在图中建立的直角坐标系中，抛物线的解析式为且过顶点C（0，5）（长度单位：m）

    【小题1】（1）直接写出c的值；
    【小题2】（2）现因搞庆典活动，计划沿拱桥的台阶表面铺设一条宽度为1．5 m的地毯，地毯的价格为20元／m2，求购买地毯需多少元?
    【小题3】（3）在拱桥加固维修时，搭建的“脚手架”为矩形EFGH（H、G分别在抛物线的左右测上），并铺设斜面EG．已知矩形EFGH的周长为27．5m，求点G的坐标．

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