一个好理解的过程0＜1＜π/2＜2＜π∴sin1＞0cos1＞0cos²1-sin²1=cos2＜0∴cos²1＜sin²1∴cos1＜sin1
π/4≈3.14/4<1π/2≈3.14/2>1即：π/4<1<π/2sinπ/4√2/2cosπ/20可见，sin1>cos1
