化简sin5π/4＋sin(﹣π)＋cos9π/4
问题描述：
化简sin5π/4＋sin(﹣π)＋cos9π/4
答
sin5π/4＋sin(﹣π)＋cos9π/4
=-sin(π/4)+0+cos(π/4)
=-√2/2+√2/2
=0可以还写详细点吗？sin5π/4＋sin(﹣π)＋cos9π/4=sin(π+π/4)-sin(π)+cos(2π+π/4）=-sin(π/4)+0+cos(π/4)=-√2/2+√2/2=0