张莉莉
幼苗
共回答了22个问题采纳率:90.9% 举报
如图,若∠
![](https://img.yulucn.com/upload/2/6b/26b75a48a22e320252c115d94939f8d0_thumb.jpg)
AOB=30°,点P在∠AOB内,且OP=2㎝,分别在 OA、OB上找一点E,F使△PEF的周长最小,并求△PEF的周长最小值。
答:OE⊥AB····························· 1分
证明:在
![](https://img.yulucn.com/upload/4/2c/42cde3cb1b7ab979bb8b0c2ee755d9c4_thumb.jpg)
和
![](https://img.yulucn.com/upload/f/d7/fd7ac1556636ea2ecce9c14ec60f26ee_thumb.jpg)
中,
∵
![](https://img.yulucn.com/upload/a/f4/af43a7ac49805febf9221cc20148f38d_thumb.jpg)
.························· 3分
![](https://img.yulucn.com/upload/b/8f/b8f2136710e648fb5243a1798bf4524e_thumb.jpg)
.
![](https://img.yulucn.com/upload/7/87/787170c1d2a42182a4682ce311dc0ca5_thumb.jpg)
.···························· 4分
∵点
![](https://img.yulucn.com/upload/9/03/90327510e89d24af803e02705a9ebb93_thumb.jpg)
是
![](https://img.yulucn.com/upload/d/be/dbe412e6ad0c7a40fa4d6f13fd419cac_thumb.jpg)
的中点
∴
![](https://img.yulucn.com/upload/5/5c/55c4ece0057570ac49472510bec1890a_thumb.jpg)
⊥
![](https://img.yulucn.com/upload/d/be/dbe412e6ad0c7a40fa4d6f13fd419cac_thumb.jpg)
····························· 6分
略
1年前
5