A、尖向<img src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/0eaa4d44-348d-4257-8fe9-fd9a6712e077.jpg" width="13" height="16" /> 面中心的圆三角形
B、支托表面呈球状突起
C、在<img src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/0eaa4d44-348d-4257-8fe9-fd9a6712e077.jpg" width="13" height="16" />边嵴处最宽，向<img src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/0eaa4d44-348d-4257-8fe9-fd9a6712e077.jpg" width="13" height="16" /> 面中心逐渐变窄
D、在<img src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/0eaa4d44-348d-4257-8fe9-fd9a6712e077.jpg" width="13" height="16" />边缘处最厚，向<img src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/0eaa4d44-348d-4257-8fe9-fd9a6712e077.jpg" width="13" height="16" />面中心逐渐变薄
E、支托底面与支托凹呈球面接触关系