点p到直线的距离L=|cosA+3sinA-6|/(根号2),要求最小值,只需求出|cosA+3sinA-6|的最小值即可.因为|cosA+3sinA-6|=|(根号10)*sin(A+B)-6|≥6-(根号10),等号仅当sin(A+B)=1时成立,其中B=arctan(1/3)...B值没用到,不算亦...