若圆x²+y²+ax+2y=0被直线x+2y+1=0平分,则圆的半径为
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![若圆x²+y²+ax+2y=0被直线x+2y+1=0平分,则圆的半径为](/uploads/image/z/2984410-10-0.jpg?t=%E8%8B%A5%E5%9C%86x%26%23178%3B%2By%26%23178%3B%2Bax%2B2y%3D0%E8%A2%AB%E7%9B%B4%E7%BA%BFx%2B2y%2B1%3D0%E5%B9%B3%E5%88%86%2C%E5%88%99%E5%9C%86%E7%9A%84%E5%8D%8A%E5%BE%84%E4%B8%BA)
若圆x²+y²+ax+2y=0被直线x+2y+1=0平分,则圆的半径为
若圆x²+y²+ax+2y=0被直线x+2y+1=0平分,则圆的半径为
若圆x²+y²+ax+2y=0被直线x+2y+1=0平分,则圆的半径为
你好,
x²+y²+ax+2y=0
(x+a/2)^2+(y+1)^2=1+a^2/4
圆心为(-a/2,-1)
因为圆x²+y²+ax+2y=0被直线x+2y+1=0平分
所以圆心在直线上,则把圆心坐标代入即可,
即:-a/2-2+1=o,a=-2
所以1+a^2/4=2
半径为根号2
希望我的回答能帮到你,满意望采纳~