题目

        honest son she has! She is proud of her son. A. What a            B. What an        C. How       D. How an   答案：B△ABC中，a，b，c分别是角A，B，C的对边，且acosA=bcosB．（1）若a=5，b=12，求|CA-CB|；（2）a=c=4，求AB•AC+BA•BC+CA•CB．