令A=arctan2,(0令B=arcsin(-1/3),(-π/2那么cos[arctan2+arcsin(-1/3)]=cos(A+B) =cosAcosB-sinAsinB =√5/5×2√2/3+2√5/5×1/3 =2√10/15+2√5/15 =(2√10+2√5)/15