∵sinx-siny=-23，cosx-cosy=23，两式平方相加得：cos（x-y）=59，∵x、y为锐角，sinx-siny＜0，∴x＜y，∴sin（x-y）=-1-cos2(x-y)=-2149，∴tan（x-y）=sin(x-y)cos(x-y)=-214959=-2145．故答案为：-2145．...