如图14,已知半径为1的与轴交于两点,为的切线,切点为,圆心的坐标为,二次函数的图象经过两点.(1)求二次函数...
问题详情:
如图14,已知半径为1的与轴交于两点,为的切线,切点为,圆心的坐标为,二次函数的图象经过两点.
(1)求二次函数的解析式;
(2)求切线的函数解析式;
(3)线段上是否存在一点,使得以为顶点的三角形与相似.若存在,请求出所有符合条件的点的坐标;若不存在,请说明理由.
【回答】
解:(1)圆心的坐标为,半径为1,,……1分
二次函数的图象经过点,
可得方程组················································································ 2分
解得:二次函数解析式为············································· 3分
(2)过点作轴,垂足为.······························································· 4分
是的切线,为切点,(圆的切线垂直于经过切点的半径).
在中,
为锐角,···························· 5分
,
在中,.
.
点坐标为························································································· 6分
设切线的函数解析式为,由题意可知,······ 7分
切线的函数解析式为···································································· 8分
(3)存在.············································································································ 9分
①过点作轴,与交于点.可得(两角对应相等两三角形相似)
,··········································· 10分
②过点作,垂足为,过点作,垂足为.
可得(两角对应相等两三角开相似)
在中,,,
在中,,
,······································ 11分
符合条件的点坐标有,······················································ 12分
知识点:相似三角形
题型:综合题