拱顶为原点,抛物线对称轴为y轴,建立平面直角坐标系.设方程为y=ax2
则 x=±2时,y=-2 代入得：a=-1/2 拱形所在的抛物线方程 为y=(-1/2)x2
一条隧道的顶部是抛物拱形,拱高是2米,跨度是4米,建立适当平面直角坐标系,求拱形所在的抛物线方程.
一条隧道的顶部是抛物拱形,拱高是2米,跨度是4米,建立适当平面直角坐标系,求拱形所在的抛物线方程.
数学人气：185 ℃时间：2020-05-14 18:57:03
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