sinx+sin2x+sin3x+.+sinnx=?求和.

sinx+sin2x+sin3x+.+sinnx=?求和. sinx*sin2x*sin3x=? 用数学归纳法证明：sinx+sin2x+sin3x+……+sinnx=[sin(nx/2)sin((n+1)x/2)]/ sin3x-sin2x+sinx=0 谁能帮忙计算一下sinx+sin2x+sin3x+~+sinnx之和,要关键步骤. 求证sinx+sin3x+sin2x=1+cos2x+cosx 解三角方程式sinx+sin2x=sin3x,0 1+sinX+sin2X+sin3X=cosX-cos2X+cos3X sin3x+cosx-cos3x-sinx/2(sin2x+cos2x) 三角函数 1.解x,2（cosx）平方+3sinx=3 2.证明（sinx-sin2x+sin3x）/(cosx-cos 求数学积分∫（sinx*sin2x*sin3x）dx sinx+sin5x+sin3x=0