f(x)=asin(πx+C)+bcos(πx+D）+4（a,b,C,D为常数）,且f(2000)=5.那么f(2004)等于?
问题描述：
f(x)=asin(πx+C)+bcos(πx+D）+4（a,b,C,D为常数）,且f(2000)=5.那么f(2004)等于?
答
f(2005)=asin(2005π+C)+bcos(2005π+D)+4
=asin(π+C)+bcos(π+D)+4
=-asinC-bcosD+4=5
asinC+bcosD=-1
f(2004)=asin(2004π+C)+bcos(2004π+D)+4
=asin(C)+bcos(D)+4
=3