1 . 已知三角形
是边长为
的等边三角形.如图,将三角形
的顶点
与原点重合.
在
轴上,然后将三角形沿着
轴顺时针滚动,每当顶点
再次回落到
轴上时,将相邻两个
之间的距离称为“一个周期”,给出以下四个结论:
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/5/ea6ae40c-45cb-442b-8319-937a33b2477f.png?resizew=172)
①一个周期是
;
②完成一个周期,顶点
的轨迹是一个半圆;
③完成一个周期,顶点
的轨迹长度是
;
④完成一个周期,顶点
的轨迹与
轴围成的面积是
.
其中说法正确的是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/5/ea6ae40c-45cb-442b-8319-937a33b2477f.png?resizew=172)
①一个周期是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f8c4c029e552954bd493b49aeab82d5.png)
②完成一个周期,顶点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
③完成一个周期,顶点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/813b03f3d13783ee2cb12a81ce6fd07b.png)
④完成一个周期,顶点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/813b03f3d13783ee2cb12a81ce6fd07b.png)
其中说法正确的是( )
A.①② | B.①③④ | C.②③④ | D.①③ |
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