函数f(x)=cosx-2cosx.sin^2a/2-sinxsina(0

问题描述:

函数f(x)=cosx-2cosx.sin^2a/2-sinxsina(0

f(x)=cosx-2cosx.sin^2a/2-sinxsina=cosx(1-2sin^2a/2)-sinxsina=cosxcosa-sinxsina=cos(x+a)
因为x=π/2时有最小值,且0