sin1=sin(π-1)π/2＜2＜π-1＜π正弦函数在(π/2,π)上单调递减,有sin2＞sin(π-1)即sin2＞sin1π/2＜2＜3＜π正弦函数在(π/2,π)上单调递减,有sin2＞sin3sin1=sin(π-1)π/2＜π-1＜3＜π正弦函数在(π/2,π)上单...