在圆O的直径CB的延长线上取一点A,AP与圆O切于点P,且∠APB=30°,AP=<img src=http://huaweicloudobs.ahjxjy.cn/e0135edae1d4aa68e1ac8591ff62283c.png width=27 height=19 style=width: 27px; height: 19px;/>则CP=( )<img src=http://huaweicloudobs.ahjxjy.cn/997d27b45abe547cb4457ef5c65a069f.png/>
①
<img src=http://huaweicloudobs.ahjxjy.cn/636cebd393fc759c2347f196a2523fd5.png/>
②
<img src=http://huaweicloudobs.ahjxjy.cn/756737956073d0b2eeab2988644809bc.png/>
③
<img src=http://huaweicloudobs.ahjxjy.cn/9f1c7b278ca516f4f5c8e3f774c3c094.png/>
④
<img src=http://huaweicloudobs.ahjxjy.cn/837c98e2a075fe450d6c5892e9ec3a84.png/>