未完成

http://cache.baiducontent.com/c?m=9f65cb4a8c8507ed4fece763105392230e54f73b6f9383167fd58448e4380c075a30b4fd74794e19979e2b2216af3f5fedf63777321420c0c18ed714c9fecf6879873045060bf24b05a219b8bc4332c050872aeab86ee5ad803384dfa3c4df25029500432097f0fa590b03ca1ee71542f4a6e81f551f4dfafa3014ae4e76599f2144b550f890256f7496f6ac4b3ac23da71506e7aa22c33405b463b36f1d3333d65bc07f465231f74e57e8454e13929a4a97296e3750a139c0aeb1b2fc49fccb9a348f8ebbb82fe433b798abad&p=882a9543d5b10af718a9d32d0214cb&newp=86788f5687904ead08e294780e569f231610db2151d6d716&user=baidu&fm=sc&query=%CD%F8%C2%E7%B1%E0%B3%CC+cmath%2819%29%3A+error+C2061%3A+%D3%EF%B7%A8%B4%ED%CE%F3%3A+%B1%EA%CA%B6%B7%FB+acosf&qid=&p1=4