<!DOCTYPE html>
<meta charset="utf-8">
<title>三角形</title>
<style type="text/css">
/*等边三角形*/
.sjx{
width:0;
height:0;
border-top:50px solid red;
border-right:50px solid transparent;
border-bottom:0 solid transparent;
border-left:50px solid transparent;
}
.dyzj{
width:0;
height:0;
border-top:0 solid transparent;
border-right:0 solid transparent;
border-bottom:50px solid green;
border-left:50px solid transparent;
}
.yuan{
width:100px;
height:100px;
border:1px solid blue;
border-radius:50px;}
</style> <!--等边三角形-->
<div class="sjx"></div>
<hr/>
<!--等腰直角三角形-->
<div class="dyzj"></div>
<hr/>
<!--圆-->
<div class="yuan"></div>
