C． d=r                                                     D． d=2r

A． d=r                                                      B． d=3r                    

9、如图，七个等圆，相邻的两个圆都外切，外面的六个圆与一个圆环都内切，若七个等圆面积之和等于圆环的面积，则圆环的宽d与小圆的半径r的关系是（   ）

A． 4                                                             B． 5                  

C． 6                                                             D． 7

8、如图，P是等边△ABC的外接圆上任一点，图中等于60°的角共有（    ）个.

C．                                     D．

A．                                              B．          

7、如图，经过点A、B的直线的解析式为（    ）

A．80                                                             B．70           

C．20                                                             D．30